Fanning's Illustrated Gazetteer of the United States.... (New York: Phelps, Fanning & Co., 1853), 221.
MIDDLESEX COUNTY, situated in the east part of Massachusetts, with Massachusetts bay on the east and traversed by the Merrimack river. Area, 800 square miles. Face of the country diversified; soil generally stony or sandy, but productive from cultivation. Seats of justice, Cambridge, Lowell, and Concord. Pop. in 1810, 52,789; in 1820, 61,476; in 1830, 77,968; in 1840, 106,611; in 1850, 161,383.