United States micropolitan statistical areas (μSA, where the initial Greek letter mu represents "micro-"), as defined by the Office of Management and Budget (OMB), are labor market and statistical areas in the United States centered on an urban cluster (urban area) with a population of at least 10,000 but fewer than 50,000 people. The micropolitan area designation was created in 2003. Like the better-known metropolitan statistical areas, a micropolitan area is a geographic entity used for statistical purposes based on counties and county equivalents. On July 21, 2023, the Office of Management and Budget released revised delineations of the various CBSAs in the United States, which recognized 542 micropolitan areas in the United States, four of which are in Puerto Rico.