Dukes County, a county of Massachusetts, consisting of a number of islands in the Atlantic ocean, with an aggregate area of 118 sq. m.; pop. in 1870, 3,787. Martha's Vineyard, the largest island, lies about 5 m. S. of Barnstable co., from which it is separated by Vineyard sound. The others are Chappaquid-dick island and No Man's Land, and the Elizabeth group. In 1872 there were 4 vessels, of 1,297 tons, engaged in the whale fishery, and 39 vessels entered and cleared in the coastwise and carrying trade. The county constitutes a customs district, of which the port of entry is Edgartown. For the year ending June 30, 1872, there were registered, enrolled, and licensed 20 vessels, with an aggregate tonnage of 2,611. Many of the inhabitants are engaged in foreign commerce. A great part of the surface is occupied by low forests, but there are cultivated tracts yielding good crops of potatoes, hay, and grain. The total value of agricultural products in 1870 was $56,280; of live stock, $63,555. Capital, Edgartown.