Union Grounds is a former baseball ground located in Brooklyn, New York. The ground was home to the New York Mutuals of the National Association from 1871 to 1875 and of the National League in 1876, the Brooklyn Eckfords of the National Association in 1872, the Brooklyn Atlantics of the National Association from 1873 to 1875, and of the Brooklyn Hartfords of the National League for the 1877 season. The ground first opened in 1862.