needs of the people who live there. These different vantage points lead to different approaches for considering rural-urban linkages, which we outline and compare in this section.

# _Functional economic areas (FEA)_

A century ago, “rural” began not far from where urban areas or city boundaries ended. Primitive communication networks and limited mobility made access to urban services from rural locations timeconsuming. With weak socioeconomic spillovers, it was reasonable to think of rural and urban as isolated from one another. By the mid-20<sup>th</sup> century improvements in transportation and ICT had changed this. Greater rural-urban spillovers increased the need for regional policy making. The growing geographical span of urban integration with their nearby hinterlands led governments to map _functional economic areas_ (FEAs), also called _functional urban areas_ ,<sup>2</sup> reflecting the rural–urban regional interdependencies and spillovers within an urban center’s “area of influence.” Functional areas are typically defined by factors such as retail catchment areas, public-service delivery areas such as for health care, and commuting flows. A key theoretical consideration in developing FEAs is the geographical reach of an urban area’s agglomeration economies into its hinterlands (Partridge, Rickman, Ali, & Olfert, 2008; Stimson et al., 2016). In practice, FEAs are typically based on commuting flows, because this data is more easily available. They then take on a local labor market definition.

The number and scope of FEAs vary by country. Most developed countries label FEAs as metropolitan areas. The United States uses counties in their construction. Some others (e.g. Canada, France, and Sweden) use rural and urban municipalities. Inclusion within a metropolitan area implies sufficient economic interdependence, which is usually proxied by commuting patterns.

FEAs often form the basis of empirical studies in planning, economic geography, regional and urban economics, and other spatially designed empirical analysis. They help understand regional economies and the economic interdependence within city-centered regions, and the significant spillovers that are generated, such as for transportation, housing, economic development, public-service provision, and environmental protection that regional policies should consider.

A related approach is that of city–region systems. Generally, a city–region encompasses nodes of human activity that tend to overlay relatively large cities with systems of medium-sized cities in proximity. City–regions, like FEAs, determine the economic and social developments of proximate suburbs, peri-urban/exurban areas, and associated rural hinterlands (Rodríguez-Pose, 2008). In fact, if properly constructed, FEAs will approximate a city–region with sufficient economic and social integration to function as a regional economy. The city–region can be a single urban center and surrounding periphery as long as there is sufficient economic and social integration—much like the definition of metropolitan areas. There also can be co-agglomerations, in which the region includes

> 2 Besides functional areas, there are a host of similar terms used across countries and academia: e.g., _functional economic areas_ , _functional economic regions, city regions, functional urban regions, metropolitan/micropolitan areas, census agglomerations, local labor market areas, commuting zones,_ and _travel-to-work areas_ (see review in Berdegué et al., 2019). For simplicity, we refer to these as FEAs.

6