| Abbott, George S., Building | Waterbury | Building | 1982 |
| Academy of Our Lady of Mercy at Lauralton Hall | Milford | District | 2011 |
| Acadian House | Guilford | Building | 1975 |
| Aeolian Company Factory Complex | Meriden | Building | 2023 |
| Ahavas Sholem Synagogue | New Haven | Building | 1995 |
| Allis-Bushnell House | Madison | Building | 1982 |
| American Mills Web Shop | West Haven | Building | 1983 |
| Andrew, William, House | Orange | Building | 2002 |
| Andrews, Moses, House | Meriden | Building | 1978 |
| Ansonia Library | Ansonia | Building | 1985 |
| Armstrong Rubber Company Building | New Haven | Building | 2021 |
| Armstrong, M. and Company Carriage Factory | New Haven | Building | 2011 |
| Atwater, George, House | Hamden | Building | 1992 |
| Atwater-Linton House | Hamden | Building | 1992 |
| Baldwin, George, House | North Branford | Building | 1977 |
| Baldwin, Timothy, House | Branford | Building | 1988 |
| Baldwin, Zaccheus, House | Branford | Building | 1988 |
| Bank Street Historic District | Waterbury | District | 1983 |
| Barker, John, House | Wallingford | Building | 1974 |
| Beach, Samuel, House | Branford | Building | 1988 |
| Beaver Hills Historic District | New Haven | District | 1986 |
| Benedict-Miller House | Waterbury | Building | 1981 |
| Beth El Synagogue | Waterbury | Building | 1995 |
| Beth Israel Synagogue | New Haven | Building | 1995 |
| Birmingham Green Historic District | Derby | District | 2000 |
| Bishop School | Waterbury | Building | 1982 |
| Blackman, Elisha, Building | New Haven | Building | 1978 |
| Blackstone House | Branford | Building | 1988 |
| Blakeslee, Joseph, House | Wallingford | Building | 1998 |
| Bradley, Timothy, House | Branford | Building | 1988 |
| Branford Center Historic District | Branford | District | 1987 |
| Branford Electric Railway Historic District | Branford | District | 1983 |
| Branford Point Historic District | Branford | District | 1988 |
| Bronson, Aaron, House | Southbury | Building | 1993 |
| Bronson, Josiah, House | Middlebury | Building | 1982 |
| Buckingham House | Milford | Building | 1977 |
| Bullet Hill School | Southbury | Building | 1972 |
| Burgis II, Thomas, House | Guilford | Building | 2000 |
| Canoe Brook Historic District | Branford | District | 2002 |
| Castle, Dr. Andrew, House | Woodbridge | Building | 2000 |
| Center Street Cemetery | Wallingford | Site | 1997 |
| Chapel Street Historic District | New Haven | District | 1984 |
| Charter Oak Firehouse | Meriden | Building | 1994 |
| Chatfield Farmstead | Woodbridge | Building | 2010 |
| Cheshire Historic District | Cheshire | District | 1986 |
| Chittenden, Russell Henry, House NHL | New Haven | Building | 1975 |
| Christ Church New Haven | New Haven | Building | 2009 |
| Colony Street-West Main Street Historic District | Meriden | District | 1987 |
| Congregation Mishkan Israel | Hamden | Building | 2021 |
| Connecticut Agricultural Experiment Station NHL | New Haven | District | 1966 |
| Connecticut Hall, Yale University NHL | New Haven | Building | 1966 |
| Cook, John, House | New Haven | Building | 1983 |
| Crawford, George W., Manor | New Haven | Building | 2015 |
| Curtis Memorial Library | Meriden | Building | 1981 |
| Curtiss, Reuben, House | Southbury | Building | 1993 |
| Dana, James Dwight, House NHL | New Haven | Building | 1966 |
| Darling Family Farmstead and Tavern (Additional Documentation) | Woodbridge | Building | 1979 |
| Darling, James Alexis, House | Woodbridge | Building | 2020 |
| Depot Street Bridge | Beacon Falls | Structure | 2007 |
| Dickerman II, Jonathan, House | Hamden | Building | 1982 |
| Dixwell Avenue Congregational United Church of Christ | New Haven | Building | 2018 |
| Downtown Seymour Historic District | Seymour | District | 1983 |
| Downtown Waterbury Historic District | Waterbury | District | 1983 |
| Dudley Farm Historic District | Guilford | District | 2023 |
| Dudleytown Historic District | Guilford | District | 1991 |
| Dwight Street Historic District | New Haven | District | 1983 |
| East Haven Green Historic District | East Haven | District | 2002 |
| East Haven High School | East Haven | Building | 2020 |
| East Rock Park | New Haven | District | 1997 |
| Edgerton | New Haven | District | 1988 |
| Edgewood Park Historic District | New Haven | District | 1986 |
| Eells-Stow House | Milford | Building | 1977 |
| Elam Ives House | Hamden | Building | 2010 |
| Eliot, Jared, House | Guilford | Building | 1985 |
| Elton Hotel | Waterbury | Building | 1983 |
| Falkner's Island Lighthouse | Guilford | Structure | 1990 |
| Farmington Canal Lock | Cheshire | Structure | 1973 |
| Farmington Canal Lock No. 13 | Hamden | Structure | 1982 |
| First Congregational Church of Cheshire | Cheshire | Building | 1973 |
| First Congregational Church of East Haven | East Haven | Building | 1982 |
| Five Mile Point Lighthouse | New Haven | Structure | 1990 |
| Fort Nathan Hale | New Haven | Site | 1970 |
| Fourth District School | North Branford | Building | 1985 |
| Frisbie, Edward, Homestead | Branford | Building | 1985 |
| Frisbie, Edward, House | Branford | Building | 1988 |
| Fulton, Lewis, Memorial Park | Waterbury | District | 1990 |
| George A. and Jennie Curtis Fay House | Meriden | Building | 2025 |
| Goffe Street Special School for Colored Children | New Haven | Building | 1979 |
| Goffe, Solomon, House | Meriden | Building | 1979 |
| Griswold House | Guilford | Building | 1975 |
| Grove Street Cemetery NHL | New Haven | Site | 1997 |
| Guilford Historic Town Center | Guilford | District | 1976 |
| Hall-Benedict Drug Company Building | New Haven | Building | 1986 |
| Hamden Bank & Trust Building | Hamden | Building | 1990 |
| Hamden High School | Hamden | Building | 1994 |
| Hamden Memorial Town Hall | Hamden | Building | 2001 |
| Hamilton Park | Waterbury | District | 1996 |
| Hammanasset Paper Mill Site | Madison | Site | 1996 |
| Harrison, Thomas, House | Branford | Building | 1988 |
| Hibbard, Enoch, House and Grannis, George, House | Waterbury | Building | 1979 |
| Hillhouse Avenue Historic District | New Haven | District | 1985 |
| Hillside Historic District | Waterbury | District | 1987 |
| Hoadley, Isaac, House | Branford | Building | 1988 |
| Hoadley, John, House | Branford | Building | 1988 |
| Hoadley, Orrin, House | Branford | Building | 1988 |
| Home Woolen Company | Beacon Falls | Building | 1984 |
| Hooker, Elizabeth R., House | New Haven | Building | 2010 |
| Hotchkiss, David, House | Prospect | Building | 1981 |
| House at 161 Damascus Road | Branford | Building | 1988 |
| House at 29 Flat Rock Road | Branford | Building | 1988 |
| Howard Avenue Historic District | New Haven | District | 1985 |
| Howd, Eliphalet, House | Branford | Building | 1988 |
| Howd-Linsley House | North Branford | Building | 1986 |
| Howe, John I., House | Derby | Building | 1989 |
| Humphreys, Gen. David, House | Ansonia | Building | 1972 |
| Hurd, William, House | Southbury | Building | 1993 |
| Hurley Road Historic District | Southbury | Building | 1993 |
| Hyland-Wildman House | Guilford | Building | 1976 |
| Imperial Granum-Joseph Parker Buildings | New Haven | Building | 1986 |
| Ives-Baldwin House | Meriden | Building | 2003 |
| Johnson, Alphonso, House | Hamden | Building | 1992 |
| Johnson, Franklin, House | Wallingford | Building | 1998 |
| Jones, Theophilus, House | Wallingford | Building | 1992 |
| Kendrick, John, House | Waterbury | Building | 1982 |
| Kraus Corset Factory | Derby | Building | 1987 |
| Laurel Beach Casino | Milford | Building | 2018 |
| Leete, Pelatiah, House | Guilford | Building | 1974 |
| Lewis, Isaac C., Cottage | Branford | Building | 1997 |
| Lighthouse Point Carousel | New Haven | Structure | 1983 |
| Lincoln Theatre | New Haven | Building | 1984 |
| Little Pootatuck Brook Archeological Site | Southbury | Site | 1990 |
| Long Wharf Pier | New Haven | Structure | 2024 |
| Madison Green Historic District | Madison | District | 1982 |
| Maltby-Stevens Factory Site | North Branford | Site | 2000 |
| Mansfield, Richard, House | Ansonia | Building | 1971 |
| Marsh, Othniel C., House NHL | New Haven | Building | 1966 |
| Matthews and Willard Factory | Waterbury | Building | 1988 |
| Meeting House Hill Historic District | Guilford | District | 1987 |
| Meigs-Bishop House | Madison | Building | 1988 |
| Mendel, Lafayette B., House NHL | New Haven | Building | 1976 |
| Meriden Curtain Fixture Company Factory | Meriden | Building | 1986 |
| Middlebury Center Historic District | Middlebury | District | 1985 |
| Milford Point Hotel | Milford | Building | 1988 |
| Miller, Henry F., House | Orange | Building | 2001 |
| Moody, Dr. Mary B., House | New Haven | Building | 2017 |
| Morris Cove Historic District | New Haven | District | 2018 |
| Morris House | New Haven | Building | 1972 |
| Mory's | New Haven | Building | 2005 |
| Mount Carmel Congregational Church and Parish House | Hamden | Building | 1991 |
| Murray, Jonathan, House | Madison | Building | 1982 |
| Naugatuck Center Historic District | Naugatuck | District | 1999 |
| Nehemiah Royce House | Wallingford | Building | 1998 |
| New England Cement Company Kiln and Quarry | Woodbridge | Site | 2001 |
| New Haven Armory | New Haven | Building | 2021 |
| New Haven City Hall | New Haven | Building | 1975 |
| New Haven Clock Company Factory | New Haven | District | 2017 |
| New Haven County Courthouse | New Haven | Building | 2003 |
| New Haven Green Historic District NHL | New Haven | District | 1970 |
| New Haven Jewish Home for the Aged | New Haven | Building | 1979 |
| New Haven Lawn Club | New Haven | Building | 2003 |
| New Haven Railroad Station | New Haven | Building | 1975 |
| Nicoll, Caroline, House | New Haven | Building | 1983 |
| Ninth Square Historic District | New Haven | District | 1984 |
| Norcross Brothers Granite Quarry | Branford | Site | 2003 |
| North Branford Center Historic District | North Branford | District | 1999 |
| Northford Center | North Branford | District | 2002 |
| Norton House | Branford | Building | 1988 |
| Old West Haven High School | West Haven | Building | 1985 |
| Orange Center Historic District | Orange | District | 1989 |
| Orange Street Historic District | New Haven | District | 1985 |
| Orange Street Historic District (Boundary Increase) | New Haven | District | 2017 |
| Osbornedale | Derby | Building | 1986 |
| Overlook Historic District | Waterbury | District | 1988 |
| Oyster Point Historic District | New Haven | District | 1989 |
| Palace Theater | Waterbury | Building | 1983 |
| Palmer, Hezekiah, House | Branford | Building | 1988 |
| Palmer, Isaac, House | Branford | Building | 1988 |
| Parsons, Samuel, House | Wallingford | Building | 1982 |
| Pine Orchard Union Chapel | Branford | Building | 2000 |
| Pines Bridge Historic District | North Haven | District | 1988 |
| Pinto, William, House | New Haven | Building | 1985 |
| Pistol Factory Dwelling | Hamden | Building | 1991 |
| Pitkin, Elisha, House | Guilford | Building | 1979 |
| Plaster House | Southbury | Building | 1993 |
| Platt, Col. Asa, House | Orange | Building | 2002 |
| Plymouth Congregational Church | New Haven | Building | 1983 |
| Prospect Green Historic District | Prospect | District | 2000 |
| Prospect Hill Historic District | New Haven | District | 1979 |
| Quaker Farms Historic District | Oxford | District | 1991 |
| Quinnipiac Brewery | New Haven | Building | 1983 |
| Quinnipiac River Historic District | New Haven | District | 1984 |
| Raynham | New Haven | Building | 1980 |
| Red Bridge | Meriden | Structure | 1993 |
| Richardson, Nathaniel, House | Middlebury | Building | 1977 |
| Rising Sun Tavern | North Haven | Building | 1979 |
| River Park Historic District | Milford | District | 1986 |
| River Street Historic District | New Haven | District | 1989 |
| Riverside Cemetery | Waterbury | Site | 1988 |
| Rogers, John, House | Branford | Building | 1988 |
| Route 146 Historic District | Branford | District | 1990 |
| Russian Village Historic District | Southbury | District | 1988 |
| Sabbathday House | Guilford | Building | 1975 |
| Salem School | Naugatuck | Building | 1983 |
| Sanford Road Historic District | Southbury | District | 1993 |
| Sanford-Humphreys House | Seymour | Building | 1982 |
| Schlaraffia Burg | New Haven | Building | 2007 |
| Scully, Vincent J. and Susannah K., House | Woodbridge | Building | 2025 |
| Seymour High School and Annex | Seymour | Building | 1983 |
| Sheffield Street Bridge | Waterbury | Structure | 2001 |
| Shelley House | Madison | Building | 1989 |
| Short Beach Historic District | Branford | District | 2019 |
| Simpson, Samuel, House | Wallingford | Building | 1986 |
| Sleeping Giant Tower | Hamden | Building | 1986 |
| South Britain Historic District | Southbury | District | 1987 |
| Southbury Historic District No. 1 | Southbury | District | 1971 |
| Southbury Training School | Southbury | District | 1992 |
| Southern New England Telephone Company Adminstrative Building | New Haven | Building | 1997 |
| Southwest District School | Wolcott | Building | 1982 |
| Southwest Ledge Lighthouse | New Haven | Structure | 1990 |
| St. Luke's Episcopal Church | New Haven | Building | 2003 |
| St. Peter's Episcopal Church | Milford | Building | 1979 |
| Stapleton Building | Waterbury | Building | 1988 |
| State Park Supply Yard | Madison | Building | 1986 |
| Sterling Opera House | Derby | Building | 1968 |
| Stick Style House at Stony Creek | Branford | Building | 1972 |
| Stone, Medad, Tavern | Guilford | District | 2009 |
| Stony Creek-Thimble Islands Historic District | Branford | District | 1988 |
| Stratford Shoal Lighthouse | New Haven | Structure | 1990 |
| Strouse, Adler Company Corset Factory | New Haven | Building | 2002 |
| Swain-Harrison House | Branford | Building | 1975 |
| Taylor Memorial Library | Milford | Building | 1979 |
| Todd, Orrin, House | Hamden | Building | 1991 |
| Tranquility Farm | Middlebury | Building | 1982 |
| Trowbridge Square Historic District | New Haven | District | 1985 |
| Tunxis Hose Firehouse | Unionville | Building | 1983 |
| Tuttle, Bronson B., House | Naugatuck | Building | 1990 |
| Tyler, John, House | Branford | Building | 1988 |
| Tyler, Solomon, House | Branford | Building | 1988 |
| US Post Office-Ansonia Main | Ansonia | Building | 1985 |
| US Post Office-Meriden Main | Meriden | Building | 1986 |
| US Post Office-Milford Main | Milford | Building | 1986 |
| US Post Office-Naugatuck Main | Naugatuck | Building | 1986 |
| Union School | West Haven | Building | 1987 |
| United States Post Office and Court House | New Haven | Building | 2015 |
| Upper Main Street Historic District | Ansonia | District | 1982 |
| Upper State Street Historic District | New Haven | District | 1984 |
| Wallingford Center Historic District | Wallingford | District | 1993 |
| Wallingford Railroad Station | Wallingford | Building | 1993 |
| Ward-Heitman House | West Haven | Building | 2003 |
| Washington Avenue Bridge | Waterbury | Structure | 2001 |
| Washington Bridge | Milford | Structure | 2004 |
| Waterbury Brass Mill | Waterbury | Site | 1975 |
| Waterbury Clock Company | Waterbury | Building | 1982 |
| Waterbury Municipal Center Complex | Waterbury | District | 1978 |
| Waterbury Union Station | Waterbury | Building | 1978 |
| Webster School | Waterbury | Building | 1982 |
| Welch Training School | New Haven | Building | 1983 |
| West Haven Green Historic District | West Haven | District | 2000 |
| West Haven VA Hospital Historic District | West Haven | District | 2022 |
| Westville Village Historic District | New Haven | District | 2003 |
| Westville Village Historic District (Boundary Increase) | New Haven | Building | 2006 |
| Wheeler, Adin, House and Theodore F. Wheeler Wheelwright Shop | Southbury | Building | 1993 |
| Wheeler-Beecher House | Bethany | Building | 1977 |
| Whitfield, Henry, House | Guilford | Building | 1972 |
| Whitfield, Henry, House NHL | Guilford | Building | 1997 |
| Whitney Avenue Historic District | New Haven | District | 1989 |
| Whitney, Eli, Gun Factory | Hamden | Site | 1974 |
| Whitneyville Congregational Church | Hamden | Building | 1995 |
| Wilby High School | Waterbury | Building | 1982 |
| Wiley-Tremaine House | Madison | Building | 2026 |
| Williams, Warham, House | Northford | Building | 1971 |
| Winchester Repeating Arms Company Historic District | New Haven | District | 1988 |
| Winchester Repeating Arms Company Historic District (Boundary Increase) | New Haven | District | 2015 |
| Wolcott Green Historic District | Wolcott | District | 2000 |
| Wood, Harcourt, Memorial Library | Derby | Building | 1982 |
| Woodbridge Green Historic District | Woodbridge | District | 2003 |
| Wooster Sawmill and Gristmill Site | Oxford | Site | 2001 |
| Wooster Square Historic District | New Haven | District | 1971 |
| Yale Bowl NHL | New Haven | Structure | 1987 |