Matanuska-Susitna Borough, Alaska

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.