Beaver is thirteen miles (21 km) long, three to six miles (10 km) wide, and forms part of Charlevoix County, Michigan. It is mostly flat and sandy, with large forested tracts. According to U.S. census data, the island has 55.773 square miles (144.45 km²) of land, and a year-round population of 551. The more densely settled portion, comprising only 6 percent of Beaver's total land area, lies within St. James Township on the northern end. This portion had a 2000 census population of 307 inhabitants. (St. James Township also includes Garden Island, High Island, Hog Island, and several smaller islands in Lake Michigan, all uninhabited on a permanent basis.) Peaine Township, taking up the remaining 94 percent of the island, contains sizable parcels of state-owned land and is mostly undeveloped.