Berkshire, a county of Massachusetts, forming the W. extremity of the state, extending across it from Vermont on the N. to Connecticut on the S., and bounded W. by New York; area, about 1,000 sq. m.; pop. in 1870, 64,827. It embraces a great variety of picturesque scenery. The surface is diversified by mountains, hills, valleys, and rolling land. In the N. part is Saddle mountain, the highest point in the state, and in the N. W. is the Hoosac tunnel, through the mountain of the same name. The soil is fertile, and well watered by the Housatonic, Deerfield, Farmington, Hoosac, and several smaller rivers. Most of the land is devoted to grazing. Marble, iron, and limestone are the principal minerals. The Boston and Albany, the Massachusetts and Vermont, the Troy and Boston, the Housatonic, and the Pittsfield and North Adams railroads traverse the county. Manufacturing is extensively carried on. There are 16 cotton mills, 2 calico print works, 41 paper mills, 27 flour mills, 16 tanneries, 10 planing and turning mills, 154 saw mills, and a great number of other manufactories.

The chief productions in 1870 were 2,828 bushels of wheat, 35,903 of rye, 156,384 of Indian corn, 248,642 of oats, 15,667 of barley, 31,901 of buckwheat, 355,670 of potatoes, 84,790 tons of hay. 1,114,343 lbs. of cheese, 1,038,751 of butter, 134,892 of maple sugar, 119,574 of wool, and 22,810 of tobacco. There were 5,028 horses, 15,834 milch cows, 14,153 other cattle, 27,195 sheep, and 4,274 swine. Capital, Pittsfield.