40 CFR 81.26: Hartford-New Haven-Springfield Interstate Air Quality Control Region.

The Hartford-New Haven-Springfield Interstate Air Quality Control Region (Connecticut-Massachusetts) consists of the territorial area encompassed by the boundaries of the following juridictions or described area (including the territorial area of all municipalities (as defined in section 302(f) of the Clean Air Act, 42 U.S.C. 1857h(f)) geographically located within the outermost boundaries of the area so delimited):

In the State of Connecticut: Cities—Ansonia, Bristol, Derby, Hartford, Meriden, Middletown, Milford, New Britain, New Haven, Shelton, Waterbury, West Haven.

Townships—Andover, Avon, Beacon Falls, Berlin, Bethany, Bethlehem, Bloomfield, Bolton, Branford, Burlington, Canton, Cheshire, Cromwell, Durham, East Granby, East Haddam, East Hampton, East Hartford, East Haven, East Windsor, Ellington, Enfield, Farmington, Glastonbury, Granby, Guilford, Haddam, Hamden, Hebron, Madison, Manchester, Marlborough, Middlebury, Middlefield, Naugatuck, Newington, North Branford, North Haven, Orange, Oxford, Plainville, Plymouth, Portland, Prospect, Rocky Hill, Seymour, Simsbury, Somers, Southbury, Southington, South Windsor, Suffield, Thomaston, Tolland, Vernon, Wallingford, Watertown, West Hartford, Wethersfield, Windsor, Windsor Locks, Wolcott, Woodbridge, Woodbury.

In the State of Massachusetts: Franklin County.

Cities—Chicopee, Holyoke, Northampton, Springfield, Westfield.

Townships—Agawam, Amherst, Belchertown, Blandford, Brimfield, Chester, Chesterfield, Cummington, Easthampton, East Longmeadow, Goshen, Granby, Granville, Hadley, Hampden, Hatfield, Holland, Huntington, Longmeadow, Ludlow, Middlefield, Monson, Montgomery, Palmer, Pelham, Plainfield, Russell, Southampton, Southwick, South Hadley, Tolland, Wales, Ware, Westhampton, West Springfield, Wilbraham, Williamsburg, Worthington.