The nodal and functional spatial organization is closely connected with the issue of balanced regional development. An even arrangement and distribution of centres of equal significance are crucial for harmonizing the spatial organization. The Republic of Croatia has quite unequal regional development. Besides lacking their own regional centre, certain parts of the country depend on centres outside those parts at a lower, subregional level. Eastern Croatia faces the issue of unbalanced development. The unbalanced spatial arrangement of towns within the urban network of Eastern Croatia is the reason why some extremely peripheral areas exist, such as Slavonska Podravina. On the other hand, southwards from Slavonska Podravina is Slavonska Posavina, the area in which Slavonski Brod has developed into a true regional centre. The development of Slavonski Brod is closely connected with its transport and geographical significance as a point of intersection and its overall position in the network of towns in the continental part of Croatia. Namely, Slavonski Brod developed at an ideal distance between two macroregional centres – Zagreb and Osijek – and, as such, the town could freely grow without the limiting effects of those larger centres (e.g. Vukovar and Vinkovci, which are closer to Osijek). Therefore, Slavonski Brod used all advantages of its position at the main longitudinal road in the countries in which it developed. Such a favourable, intersecting position also enabled an intensive economic development, which in turn incited demographic growth, which promoted Slavonski Brod as the fully developed regional centre, with a population of around 60,000, of the southeastern part of Eastern Croatia, i.e., the area of Slavonska Posavina and Požeška kotlina (The Požega Valley). Nevertheless, it must be said that the nodal and functional region of Slavonski Brod is not an entirely homogeneous area. The longitudinal distribution of the region influenced its western part, with Nova Gradiška as a subregional centre, which is more distant from the regional centre, to have more unfavourable developmental trends than its eastern part, in which the regional centre itself is located. Apart from analysing the Slavonski Brod urban area, this paper aims, based on an analysis of its nodal region, to establish the place and significance of Slavonski Brod in the urban system of Eastern Croatia. The quantitative and qualitative spatial analyses are expected to define its gravitational area as a regional centre and show whether some areas, traditionally considered to gravitate to Slavonski Brod (e.g., Nova Gradiška subregion), still gravitate to Slavonski Brod or Zagreb. This paper will deal with the growth and significance of Slavonski Brod on three levels. The first level is an analysis of the city itself, its development and its functions. The second level analyses the urban region. The city's influence on complex processes of transforming the suburban surroundings within the daily urban system will be analysed. Based on analysing the movement of people, goods and information, the third level analyses the city’s influence on a broader gravitational area – the nodal region and processes within it. The employment rate growth was proportionate to the threefold increase in the Slavonski Brod population in the period 1948 – 1971 and to subsequent milder growth. The jobs in the urban area of Slavonski Brod in the secondary and tertiary industries outnumbered the available local workforce. Therefore, daily migrations of the employed played an important role, which was enabled by solid transport connections of Slavonski Brod with its surroundings. The possibility for the population to get employed in the city, as the labour centre, caused the deagrarianization of the rural population and, consequently, the transformation of the surroundings. In that context, the following hypothesis will be tested: Slavonski Brod has formed its urban region with its heterogeneous characteristics. Due to better transport connections with the city, the northwestern, western and eastern parts of its region are more urbanized and hence the region has a distinctive, elongated shape. The most critical nodal region integration factor is functional connections and relations within the region expressed through the movement of people, goods, ideas, money, information etc. Given its configuration, i.e., the elongation of the area and the location of the central settlement itself poses a critical question we will try to answer: To what extent does Slavonski Brod as the regional centre affect the previously mentioned western part of the nodal region? This also touches on the second hypothesis, as follows: The gravitation of the western part of the Slavonski Brod region (Nova Gradiška area) to Slavonski Brod is in decrease, while this region is increasingly gravitating to Zagreb; furthermore, due to the weakened development of functions in Slavonski Brod, its influence as the regional centre has been diminished in the southwestern part of Eastern Croatia (the Osijek macroregion). The main task of this paper is to analyse the urban and nodal region, i.e., the size and spatial coverage of the gravitational area of Slavonski Brod and the orientation of the local population to large urban centres to meet the basic needs. This is why different quantitative and qualitative indicators are analysed to establish the following: 1. The dependency of the Slavonski Brod region population on functions possessed by Slavonski Brod, 2. How equipped are settlements of the Slavonski Brod region with central functions, and 3. Possible dependency of the populace by higher-rank functions in some other towns outside this region. This research has mostly been conducted based on the desk method and fieldwork. Apart from the available literature and statistical data from different sources, individual field investigations were done, like the gravitational orientation of the local population. The gravitational orientation was investigated using survey research. First, using the cataloguing method, central functions were catalogued, and then, using the internet sources analysis and before the field investigation started, recorded was the majority of institutions and institutes in the Slavonski Brod area which belong to central functions. Afterwards, a field visit confirmed their validity and the functions unavailable without the Internet were recorded. The central functions were recorded according to the six essential groups: (1) education, (2) healthcare, (3) telecommunications, (4) supply, (5) finance and (6) administration. Using the survey research method, an analysis was conducted in 2015 of the range of central functions of Zagreb, Osijek Slavonski Brod and other towns in the Slavonski Brod region to investigate the spontaneous gravitation of the local population regarding the supply of goods and services. This research follows up on a similar one conducted in the Nova Gradiška area (Dragić, Njegač and Šulc, 2018.) using the same methodology, which is also used to establish the true significance of Slavonski Brod as the gravitational centre of the Nova Gradiška area. According to the 2011 census, the population of Eastern Croatia was 805,998. The development of this region’s population has two phases. The first is the population growth from the Second World War until 1991 and the War of Independence. Since 1991, this region recorded a decrease in population (depopulation) in the periods 1991 – 2001 and 2001 – 2011 between the censuses. Eastern Croatia is the least urbanized macroregion. Larger towns are situated along the rim, leading to unequal urbanization and an increase in population migration, especially in the northwestern part, which has no larger towns. Therefore, the demographic indicators of Eastern Croatia point to depopulation processes, regional concentrations and the unfavourable age structure of the population. It is certain that relatively large urban centres and their neighbouring settlements, despite the migration of young, qualified workforce, have a better demographic prospect than remote rural settlements due to the poor economic situation. The agriculture of Eastern Croatia is characterized by small-sized agricultural households and an elderly workforce. The concentration of the employed is significant in the tertiary and quaternary sectors, with the largest share of the employed, primarily owing to the development of central-place functions in urban centres of Eastern Croatia. However, the urban-based industry is significant in Osijek, Slavonski Brod, Vinkovci, Vukovar, Požega, Donji Miholjac, Valpovo, Beli Manastir, Našice, Orahovica and Županja. Slavonska Posavina is the area bordered by Psunj, Babja gora and Dilj gora on the north, and the Sava River on the south. Slavonski Brod is located in the eastern part of Slavonska Posavina, at the foot of Dilj hill, where it nears the Sava River, due to which the low underwater zone beside the river is narrowed thus enabling an easy crossing over the Sava River. In the late 19th and early 20th century, Slavonski Brod developed into a significant industrial centre owing to its favourable position near the navigable Sava River and the railway. Until 1991, Slavonski Brod was a polyfunctional labour centre with a dominating industry. This was followed by the war, during which the economy of Slavonski Brod suffered heavy damage. The industry of Slavonski Brod, which is focused on two industries – the metal processing industry in a broader sense and the wood processing industry is directly affected by the reorganization of the economy and new market conditions, which caused a drop in production and exports and an increase in insolvency and unemployment. The general situation in 2011 was somewhat better; the total number of the employed was on the increase and, by the sectors, the highest number of the employed was in the quaternary, secondary and tertiary, and the lowest number of the employed was in the primary sector. A mild but insufficient economic recovery took place. The small enterprise sector gradually became a carrier of the city's economic activities. Therefore, the independence of the Republic of Croatia changed the role of Slavonski Brod, which became a border town. A change in the social and political system, i.e., the development of the market economy and ownership and legal relations of the private sector, caused functional changes in the town, manifested in the weakening of the secondary (industrial) functions as the basis of the development, and in tertiarization, i.e., development of the service sector. This influenced the growth in the number of employees in the tertiary, especially in the quaternary sector. The city development encouraged a significant concentration of service functions of the tertiary and quaternary sectors in the city. Slavonski Brod functions as a service centre for the population of its immediate and broader surroundings. The new political and territorial structure in 1991 contributed to this, by which Slavonski Brod became the county centre. Numerous activities were strengthened in Slavonski Brod, including public, educational, health, financial, cultural, telecommunications and trade. According to the degree of development of these central functions, Slavonski Brod is a service centre of regional significance. Municipal and county administrative bodies are located in Slavonski Brod. Slavonski Brod University of Applied Sciences was founded in the city, strengthening its educational function. Then, in addition to the General Hospital, polyclinics and many specialist surgeries were established in the city. By opening a number of bank branches, mostly foreign ones, the financial function of the city has also been strengthened. In the observed periods, the suburban surroundings of Slavonski Brod increased by the population immigration far more than by natural increase, which primarily applies to the city itself and the settlements making a territorial continuity therewith. Immigration influenced population renewal, leading to a slightly more favourable population age structure in the city and suburban settlements. Strengthening the central functions of Slavonski Brod created the centrifugal forces of the city that started the process of structural transformation of the surroundings. As a result, the immediate surroundings gradually absorbed a part of the immigration pressure on the city, i.e., certain city parts developed into suburbia, thus slowly becoming an integral part of the broadened urban area of Slavonski Brod. Similar tendencies are present in other parts of the city's surroundings but are modified by their distance from the city. From 2001 – 2011, the city and its surroundings had a negative natural change and negative migration balance except for a part of the northeastern sector, which was the consequence of an unfavourable economic situation. The population growth is a result of immigration, partly from war-affected Bosnia and Herzegovina but also the immigration from other municipalities of the same county. The tendencies towards suburbanization and increased spatial mobility of the population are pronounced, especially in the northeastern and eastern sectors but also along the main transport corridors. In general, the share of immigrants decreases with the degree of socioeconomic transformation of the settlement, as does the population dynamics. Thus, the largest share of immigrants near the City of Slavonski Brod is in the more urbanized northeastern and eastern sectors of the surrounding area, which are more attractive to settle. A slightly lower share belongs to the northeastern and northern parts, and the smallest share belongs to the southeastern sector of the urban region. Based on the differences in the number of inhabitants of the city and its surroundings and the overall development of the population, it can be concluded that the city region of Slavonski Brod is characterized by relative centralization – the population growth is present both in the city and its surroundings, with the city's growth being more considerable. However, a gradual transition to the decentralization phase can be observed, with the population decline in both the city and its surroundings, i.e. the entire region, except for the increase in the population of more heavily urbanized settlements in the northeastern sector. The data of the 2021 population census will probably show this. The intensity of daily migration of employees to Slavonski Brod from the settlements of the city region is the highest, with 68.5% of all migrants out of the total number of employees. Settlements with over two-thirds of migrants to Slavonski Brod form a circular zone around the city of unequal width in particular sectors. The settlements from which more than two-thirds of the employees who work in Slavonski Brod come are located mainly on the main roads or in the immediate vicinity of the city. The share of daily migrants decreases with distance from the city. However, given the smaller number of lines of the suburban transport system, the number of daily migrants to Slavonski Brod would decrease without the increase in the level of personal motorization as recorded in the last decade. Therefore, owing to the development and expansion of the work function of Slavonski Brod, the suburban area is being urbanized. This develops urbanized zones around cities. In particular, the value of suburban surroundings increases with strengthening the daily workforce migrations and decreased population migration from rural to urban areas. This causes socioeconomic, functional and morphological transformations of the surrounding settlements. The work function thus influenced the social reorganization of the population and changes in the socioeconomic, physiognomic and functional structure of settlements, i.e., changes in their urbanization. More urbanized settlements make a continuous zone in the northeastern and eastern parts of the urban region. On the other hand, the urbanization axis, although of a lower degree, is noticeable in the northwestern part along the main transport corridor. The northern and southeastern parts of the region have a lower urbanization degree. In peripheral, transportation-wise isolated parts of the region, most settlements are rural with unfavourable characteristics. However, being dependent on the city, these settlements are functionally an integral part of the urban region. The urban region of Slavonski Brod is heterogeneous and elongated along the main road in the west-east direction, which confirms the first hypothesis. 69.3% of the population is settled in Slavonski Brod. The population of more urbanized and mainly less urbanized settlements is proportionate to their share in the total number of settlements. It is unfavourable that almost one-fifth of the population in the surroundings lives in a large number of small, poorly urbanized settlements. Therefore, many small settlements in the region have an unfavourable urban settlement structure. From 2001 to 2011, all parts of the Slavonski Brod area had an unfavourable population migration due to emigration processes and decreased natural increase, accompanied by an insufficient offer of new jobs to keep the population able to work. The highest decrease in population is in peripheral parts of the Slavonski Brod region – moving further from Slavonski Brod, the unfavourable migration of the population gets more and more increased. The only sector in the immediate urbanized suburban surroundings of the city of Slavonski Brod where the population is in increase is the northeastern sector. The work function in these centres is underdeveloped, and hence the population able to work is forced to move out. On the other hand, the suburban surroundings and the city of Slavonski Brod alone are attractive for settling. Slavonski Brod is the most developed centre, although the industry is going through a recession. The city has the highest-rank central functions, with its most developed work functions being attractive for settling. Stable transport connections of the suburb with the city also make the city surroundings attractive for settling. After the Second World War, Slavonski Brod developed into a powerful work centre that attracted the population not only from the Slavonski Brod area but also from Bosnia and Herzegovina through its industry and other functions. The immigration from Bosnia and Herzegovina was in phases; it began with the industrialization of Slavonski Brod, which was most intense in the 1960s and the 1970s. It continued similarly later on, but on a lower scale. Due to the war in Croatia and Bosnia-Herzegovina in the 1990s, there was a great wave of migration from Bosnia and Herzegovina. That was why Slavonski Brod was not so dependent on the workforce from the Slavonski Brod area. However, Slavonski Brod was being settled by a population from remote rural parts of the Slavonski Brod area. That is how the Slavonski Brod population was renewed and increased during the unfavourable natural increase not only of the city but from its suburban surroundings as well. The most intense daily migrations from the Slavonski Brod area are towards the City of Slavonski Brod, the most developed work centre of the Slavonski Brod area. Strong development of industry and other business activities of Slavonski Brod and, on the other hand, insufficient development of other work centres in the Slavonski Brod area caused a significant polarization of the work function in Slavonski Brod and, consequently, the gravitational orientation of the daily migrations towards the city. Apart from Slavonski Brod, smaller work centres with their gravitational areas are present in the Slavonski Brod area. The most intense daily migrations of the employed are from the immediate surroundings of Slavonski Brod and the transport corridor in the west-east direction. As we move away from Slavonski Brod, the intensity of daily migrations weakens. An analysis of daily interactions in Slavonska Posavina shows their pronounced weakening in the western part (the Nova Gradiška area), which confirms the thesis of a lower influence of Slavonski Brod on that area. The work function in the Slavonski Brod area came to polarize as a result of the dominant role of settlements of the highest degree of centrality in the population employment. The functional and physiognomic transformation in the Slavonski Brod area in 2011 was the most intense in the areas closer to the City of Slavonski Brod and smaller work centres. This transformation weakens as the distance from them increases. Urbanization zones are broader, and the transport availability is proportionate to the intensity of the transformation, which is hindered by the elongation of the urbanization zones along the main transport corridors. Therefore, apart from more intense urbanization, the more pronounced centralization and spatial polarization of the population in the city also took place. Being the first to have been involved in the urbanization and industrialization processes, Slavonski Brod and the suburban settlements of Brodski Varoš and Podvinje are the only urban settlements in the Slavonski Brod area. Owing to their socioeconomic, functional and physiognomic features, as broadened urban areas, these settlements were categorized as urban settlements. Only two settlements are more urbanized – Bukovlje in the eastern part and Gornja Vrba in the northeastern part of the immediate urbanized suburban surroundings. These settlements are significant and are also gathering centres of the lowest level. Less urbanized are settlements that are smaller but still underdeveloped work centres. The majority of municipal centres of the Slavonski Brod area and settlements near the city centre with a favourable transport position also belong to this category. Although this category includes settlements with a population of 2000 and more, their functions are still underdeveloped and do not meet the other criteria for being classified into the group of more urbanized settlements. Rural settlements are quite remote places not included in the urbanization process. Their peripheral position compared with work centres is reflected in their demographic structure, and those settlements have a small population with households with elderly members. The northwestern, western and eastern parts of the Slavonski Brod area have more urbanized settlements along the transport corridors, and the northern, southwestern, southeastern and end eastern parts have a smaller number of urbanized settlements given their peripheral position in relation to Slavonski Brod and transport corridors. Therefore, the Slavonski Brod area is generally less urbanized. This paper analyses the central functions of settlements in the Slavonski Brod area, where the gravitational orientation of the population towards larger cities is observed. It turned out that the whole area was deficient in primary functions except for Slavonski Brod. Slavonski Brod has the centre functions of the 4th degree of centrality. However, this area is not fully covered by a developed network of central settlements despite the existence of a certain number of those with lower degrees of centrality. Today, given the number and type of functions they possess, Bebrina, Donji Andrijevci, Oriovac and Velika Kopanica have the 2nd degree of centrality. Brodski Stupnik, Bukovlje, Garčin, Gornja Vrba, Gundinci, Klakar, Oprisavci, Podcrkavlje, Sibinj, Sikirevci, Slavonski Šamac and Vrpolje have the 1st degree of centrality. Thus, out of 93 settlements in the Slavonski Brod area, 17 have centrality, while 70 have not. Six out of 70 settlements without centrality have particular functions and, therefore, can be said to have partial centrality. On the other hand, Slavonski Brod, on the regional gravitational level, is insufficiently functionally equipped to meet all the needs of its population. For that reason, the population occasionally or regularly circulate to Zagreb or the somewhat closer regional centre of Osijek. Both centres have almost equal gravitational capacity in this area despite a considerable difference in their distance. The problem is not even the number and type of functions but their quality. This is why some respondents prefer going to Zagreb because of the estimated better quality of services (e.g., education and healthcare). Some respondents prefer going to Osijek due to the better cultural services. An additional problem is rather inadequate public transportation connection within the Slavonski Brod area and poor connections with Zagreb and Osijek. Therefore, the passenger car is the dominant means of transportation. The Nova Gradiška area is deficient in essential functions, with the partial exception of Nova Gradiška, which partly influenced the depopulation of this area. However, at the subregional level of gravity, Nova Gradiška is not sufficiently functionally equipped to meet the appropriate needs of its region's population. This is why the local population occasionally or regularly goes to Slavonski Brod, the nearest regional centre, and to Zagreb, which has the ranking functions and the most diverse services. Considering the current demographic and socioeconomic trends, particularly intensive emigration, unfavourable trends are expected to continue. The population decrease may consequently lead to the functional weakening of the entire area, including Nova Gradiška, which will additionally increase the gravitation to larger centres outside the Nova Gradiška area. An equal intensity of circulation is also expected towards Slavonski Brod and Zagreb. However, in the case of a more intense decrease in population and functional weakening, a change in the relation of the gravitational orientation in favour of Zagreb is possible. Nevertheless, the orientation of the Nova Gradiška area population towards higher-rank functions in Slavonski Brod rather than Zagreb is still more pronounced, by which the second hypothesis of work is rejected. Thus, Slavonski Brod still plays the role of the regional centre of the western part of its region, i.e., the Nova Gradiška area.