We study a general family of economic geography models that features
endogenous agglomeration. In many-region settings, the spatial scale---"global"
or "local"---of the dispersion force(s) in a model plays a key role in
determining the resulting endogenous spatial patterns and comparative statics.
A global dispersion force accrues from competition between different locations
and leads to the formation of multiple economic clusters (or cities). A local
dispersion force is caused by crowding effects within each location and induces
the flattening of each city. By distinguishing local and global dispersion
forces, we can define three prototypical classes, namely, models that have only
global, only local, and both local and global dispersion forces. The three
model classes engender qualitatively different spatial patterns. Multiple
cities are formed only when a global dispersion force is at work; otherwise,
only a unimodal distribution can be formed. A city can have its spatial extent
only when a local dispersion force is at work. A wide variety of extant models
are reduced into the three prototypical classes. Our framework adds consistent
interpretations to the empirical literature and also provides general
\Red{insights into} treatment effects in structural economic geography models.Comment: Main text: 53 pages, 18 figure