In the United States a Metropolitan Statistical Area (MSA) is a
geographical region with a relatively high population density at
its core and close economic ties throughout the area. Such
regions are not legally incorporated as a city or town would be,
nor are they legal administrative divisions like counties or
sovereign entities like states. As such the precise definition
of any given metropolitan area can vary with the source. A
typical metropolitan area is centered on a single large city
that wields substantial influence over the region (e.g.,
Chicago, or Atlanta). However, some metropolitan areas contain
more than one large city with no single municipality holding a
substantially dominant position (e.g., Dallas–Fort Worth
metroplex, Riverside–San Bernardino or Minneapolis–Saint Paul).
MSAs are defined by the U.S. Office of Management and Budget
(OMB), and used by the U.S. Census Bureau and other federal
government agencies for statistical purposes. The U.S. Office of
Management and Budget (OMB) defines a