Matanuska-Susitna Borough, Alaska

Matanuska-Susitna Borough, Alaska
Location within the U.S. state of Alaska
Coordinates: 62°24′N 149°35′W / 62.4°N 149.58°W / 62.4; -149.58
Country United States
State Alaska
IncorporatedJanuary 1, 1964
Named afterMatanuska River and Susitna River
SeatPalmer
Largest CDPKnik-Fairview
Government
 • Borough MayorEdna DeVries
Area
 • Total
25,258 sq mi (65,420 km2)
 • Land24,608 sq mi (63,730 km2)
 • Water650 sq mi (1,700 km2)  2.6%
Population
 (2020)
 • Total
107,081
 • Estimate 
(2024)
117,613
 • Density4.3515/sq mi (1.6801/km2)
Time zoneUTC−9 (Alaska)
 • Summer (DST)UTC−8 (ADT)
Congressional districtAt-large
Websitewww.matsugov.us

Matanuska-Susitna Borough (often referred to as the Mat-Su Borough) is a borough located in the U.S. state of Alaska. Its borough seat is Palmer, and the largest incorporated community is Wasilla. As of the 2020 census, the borough's population was 107,081.

The borough is part of the Anchorage Metropolitan Statistical Area, along with the municipality of Anchorage on its south.

The Mat-Su Borough is designated as so because it contains the entire Matanuska and Susitna Rivers. They empty into Cook Inlet, which is the southern border of the Mat-Su Borough. It is one of the few agricultural areas in Alaska.