CHELMSFORD, a town of Middlesex county, Massachusetts, U.S.A., in the north-eastern part of the State, adjoining the city of Lowell. It lies on both sides of the Concord river, and is served by the New York, New Haven and Hartford railroad. The popula tion in 1930 was 7,022 Federal census. It has numerous factories. Chelmsford is first mentioned in the records of the State in Lowell was set off from it in 1826.