Metropolitan Statistical Area
A geographic cluster of population defined by the United States Census Bureau. An MSA includes a city of at least 50,000 people or urbanized area of at least 100,000 people and the counties that include these areas.
Not all areas of the U.S. are in an MSA. There are over 300 regions of the country designated as MSAs. The remaining areas are identified by RSAs (Rural Service Areas). All counties in the country are within either an MSA or RSA. MSAs comprise 76% of the U.S. population, but only 22% of its land surface area.
MSAs and RSAs are the divisions that were used by the FCC to geographically separate cellular radio frequency (spectrum) licenses that were granted to wireless (cell phone) carriers in the 1980s. This includes the 800/850 MHz bands. Other bands, such as PCS (1900 MHz) used MTA and BTA divisions instead.
In order for a wireless carrier to provide service to a specific MSA or RSA, it must have an FCC license for that area. Two licenses were originally assigned per MSA/RSA, for slightly different radio frequency sub-bands. Since they were first assigned, most cellular licenses have been sold and/or sub-divided, both by geography and radio frequency.