Hertfordshire, Or Herts an inland county of England, bordering on Cambridgeshire, Essex, Middlesex, Buckinghamshire, and Bedfordshire; area, 611 sq. m.; pop. in 1871, 192,226. Its principal rivers are the Colne and Lea with their tributaries, affluents of the Thames, and some smaller streams flowing to the Ouse. Part of the New river, which supplies London with water, is within the shire, and is conducted by an aqueduct along the valley of the Lea. The Grand Junction canal passes through the county. It is also traversed by the London and Northwestern and Great Northern railways, while the Eastern Counties railway skirts the S. E. boundary. In the northern part of the county are several ranges of chalk hills, which attain an elevation of 900 ft. above the sea. There are manufactories of straw goods, ribbons, paper, and malt, but the principal industry is agriculture, seven eighths of the county being arable land. In the S. W. part are extensive apple and cherry orchards. There are many Roman and other antiquities, of which the most prominent are St. Alban's abbey and the ruins of Berkham-stead castle, and Roystone church and cave.

Capital, Hertford.