Rural-Urban Commuting Area Codes (RUCA)

Key facts

Maintained by

USDA Economic Research Service (ERS)

Geographic unit

Census tract, with a ZIP code approximation

Primary codes

1 to 10, with secondary codes for finer detail

Current base

2020 census; earlier versions based on 1990, 2000 and 2010

HHS rural use

HRSA treats metro-county tracts with RUCA codes 4 to 10 as rural

What are RUCA codes?

RUCA codes classify places by how urban they are and how closely they are tied to urban centers through commuting. The USDA Economic Research Service (ERS) builds them from census urban area definitions and commuting flow data, assigning a code to every census tract.

Because they work at the tract level, RUCA codes can separate a remote rural tract from a suburb inside the same county, which county-based classifications cannot.

How RUCA codes are structured

The 10 primary codes combine the size of the urban core a tract belongs to or commutes to, and the share of workers commuting there:

• Codes 1 to 3: metropolitan. Code 1 is the core, code 2 has a high commuting share (30 percent or more) to the core, code 3 a low share (10 to 30 percent).
• Codes 4 to 6: micropolitan cores and their commuting areas, following the same pattern.
• Codes 7 to 9: small town cores and their commuting areas.
• Code 10: rural tracts whose main commuting flow is local or to another rural tract.

Why RUCA codes matter

Many federal programs define rural using RUCA codes. The HRSA Federal Office of Rural Health Policy treats census tracts with codes 4 to 10 inside metropolitan counties as rural, alongside all nonmetropolitan counties and certain large or rugged tracts, which determines eligibility for rural health grants. Researchers use RUCA codes to compare rural and urban access, outcomes and provider supply, and commercial teams use them to segment territories more precisely than by county.

RUCA codes vs county-based classifications

County-level systems, such as the Office of Management and Budget metropolitan and nonmetropolitan delineations and the ERS Rural-Urban Continuum Codes, label an entire county with one category. Large western counties that contain both a city and vast rural land end up labeled metropolitan. RUCA codes avoid that problem, but the ZIP code version is an approximation built from tracts, so joining by ZIP adds error.