Stretching west from Boston to include most of the communities inside the I-495 corridor, the MAPC planning area consists of 22 cities and 79 towns. Coastal communities, older industrial centers, rural towns, and modern cities are represented within the 1,422 square miles that comprise the MAPC region. According to the 2000 Census, the region's population is 3,066,394. MAPC works with its 101 cities and towns through eight subregional committees.

Detailed Map of Subregions and List of 101 communities