The decentralisation and fragmentation of local governments have been studied in a broad range of social sciences (Goodman, 2015; Xin & Chen, 2023). Approaches to decentralisation have differed in the reforms focused on transferring powers, responsibilities, and resources from the central government level to elected authorities at the subnational level for a wide variety of political, historical, and economic reasons (OECD, 2019). Local government systems have been described as ‘fragmented’ (and as ‘not consolidated’) when they have a large number of local governments (Goodman, 2015) and when local areas have multiple or even many local government units (e.g., Schneider, 1986; Goodman, 2019), usually measured in absolute or per capita terms. Sometimes, the term ‘fragmented’ is used to describe situations when excessive numbers of local government units exist, and adjectives like ‘high’, ‘excessive’, and ‘extreme’ are added to emphasise the level of fragmentation (e.g., Martinez-Vazquez & Gomez-Reino, 2011; Škarica, 2021; Hoffmann-Martinot, 2003). Horizontal and vertical fragmentation are usually differentiated: horizontal fragmentation relates to the number of units within the same tier of local government, and vertical fragmentation is considered closer to the notion of decentralisation and refers to the multi-level structure of local government and the distribution of responsibilities across its units (Goodman, 2019; Jong et al., 2021). The term ‘fragmentation’ may be used not only for referring to the high number of local governments but also to the processes that lead to fragmentation (i.e., splitting administrative units into a larger number of smaller units) (Grossman et al., 2017). There are mixed opinions on which local government systems are ‘fragmented’ and which are ‘territorially consolidated’ (Swianiewicz, 2002).