In the context of current metropolitan areas, it is the region that represents the most complete unit of economic, social and ecological structure. This fact points to the logic of establishing regional governance. However, resistance to regionalism is widespread. Briffault argues that this resistance is due to political reasons rather than theoretical ones. People do not disagree with the notion of the region as a socio-economic and ecological entity, but they do tend to see regionalism as a step toward centralization and a shift of power from local governments. Therefore, resistance to regionalism usually stems from the self-interests of local officials, firms, and other interest groups who benefit from strong local autonomy and regional fragmentation.

The primary challenge for regionalism is the establishment of legal and political structures to represent metropolitan areas. Certain special purpose bodies, such as watershed corporations, exist now but are unlikely to be able to integrate different public concerns, and also cannot keep up with the rapid changes that take place in metropolitan regions. As a first step, regionalists call for new regional processes, structures, or institutions that can identify regional problems, formulate regional solutions, implement those solutions, and coordinate regional actions (6).

Briffault also points out that regionalism has experienced resurgence since the 1990s. There are three reasons for this: exacerbating urban sprawl, concentration of poverty in inner-cities, and increasing competition in the new global economy. The global market sees a region as a competitive actor. Also, regionalism can be seen as a democratic tool in areas that have uneven distribution of wealth and a high degree of urban sprawlthe economic and social groups that have been separated by these forces have equal representation in a regional government.

On the other hand, advocates of localism argue that decentralization of power enhances efficiency, democracy and self-determination. They argue that decentralization allows municipalities to customize their public services to specific local needs, which gives citizens more opportunity to choose municipalities based on their preferences. Also, localism is said to promote democracy by making citizen participation more accessible and increasing the sense of community and ownership.

The reality of contemporary metropolitan areas, however, undermines most of these arguments. First, local actions often produce external economies and diseconomies, the significance of which increases in metropolitan areas where borders between municipalities are less relevant. Tiebouts efficiency model, one basis of the argument for localism, depends on the assumption that consumers are mobile and will shop around different municipalities.  This is not realistic when you consider that zoning and availability of jobs greatly limits the mobility of people. In metropolitan areas externalities can be avoided, mobility protected and the opportunity of poorer localities to make choices among public services secured only at the regional level (20).