The Community of Big Lake is a non incorporated city with a population of about 2000. It is located within the Matanuska-Susitna Borough.

The Matanuska-Susitna Borough is situated within the heart of Southcentral Alaska, encompassing more than 24,000 square miles (about the size of the state of West Virginia). The Borough includes mountain ranges and valleys; glaciers, rivers, and lakes; wetlands, tundra, and boreal forest; farms, towns, suburban homes, and isolated cabins; and vast stretches of pristine wilderness. Its boundaries enclose the drainages of its two principal rivers-- the Matanuska and the Susitna Rivers. The Borough includes portions of the Alaska Range with the tallest mountain in North America, Mount McKinley, just outside its northern borders; portions of the Chugach Mountains to the south; and virtually the entire Talkeetna and Clearwater Ranges in its interior. The Municipality of Anchorage, Upper Cook Inlet, and Knik Arm delineate the Borough's southern border.

The Borough was incorporated as a second class general law borough in 1964 and has a manager form of government. It includes the three incorporated cities of Houston, Palmer, and Wasilla.

The 1970 federal census counted 6,509 persons in the Borough. By 1980, the Borough's population had grown to 17,816; and the 1990 Borough census found 39,638 persons. The Borough's population continues to grow, with an estimated 52,000 residents in 1995. Approximately 37 percent of the Borough's employed person's work outside the Borough; 27 percent in Anchorage, 5 percent in the North Slope Oil Fields, and 5 percent elsewhere.