County planning is generally considered as in the nature of regional planning, with the county as the planning unit and county lines as the boundary lines of the region. Official county-planning commissions are operating in Los Angeles and Santa Barbara Counties, Calif.; Glynn County, Ga.; Detroit and Wayne County, Mich.; Mercer County, N.J.; Putnam, Onondaga, and Monroe Counties, N.Y.; Hamilton and Lucas Counties, Ohio; Allegheny County, Pa., and Milwaukee County, Wis. In many instances the areas in which regional planning is most desirable and to which it is best applicable are not those limited by the existing lines of any single political unit, as town or county, but overlap such lines, making the appropriate planning body a regional-planning commission whose jurisdiction may include parts of one or more counties or parts of one or more states [Lester G. Chase, Survey of City Planning and Related Laws in 1929 (mimeographed circular; Division of Building and Housing, U.S. Dept. of Commerce, 1930)].