| Moreland Valve | Manchester | CT |
| Morgan Street Public Siding | Hartford | CT |
| Morgan Street Siding | Hartford | CT |
| Morganti | Plantsville | CT |
| M. Seward & Sons | New Haven | CT |
| Mt. Sinai Hospital | Hartford | CT |
| M.V. Moraghan | Litchfield | CT |
| Nancy Lynn Bakeries | Bridgeport | CT |
| Nancy Lynn Bakery | Bridgeport | CT |
| National Essential Oils Distilling | Chester | CT |
| National Fire Insurance | Hartford | CT |
| National Folding Box & Paper | New Haven | CT |
| National Gypsum | New Haven | CT |
| National Manufacturing | Plainfield | CT |
| National Plainfield | Plainfield | CT |
| National Plumbing & Heating | New Haven | CT |
| National Sintered Alloys | Danbury | CT |
| Naugatuck Chemical | Naugatuck | CT |
| Naugatuck Chemical | Waterbury | CT |
| Naugatuck Chemical | Hartford | CT |
| Naugatuck Malleable Iron | Naugatuck | CT |
| Naugatuck Malleable Iron | Union | CT |
| Naylor School | Hartford | CT |
| Nbr 683 Kdl Lab - Greenberg | Windsor | CT |
| Nelson Fabricating | Norwalk | CT |
| Neron Insulation | Hartford | CT |
| Nestle | New Milford | CT |
| New Britain General Hospital | New Britain | CT |
| New Britain High School | New Britain | CT |
| New Britain Hospital | New Britain | CT |
| New Britain Incinerator | New Britain | CT |
| New Britain Machine | New Britain | CT |
| New Britian Trust | New Britain | CT |
| New Canaan Sheetmetal | New Canaan | CT |
| New Canoan High School | Hartford | CT |
| New Danbury High School | Danbury | CT |
| New Departure | Bristol | CT |
| New England Alloy Casting | Hartford | CT |
| New England Engineering | Waterbury | CT |
| New England Engineering | Norwalk | CT |
| New England Engineering | New London | CT |
| New England Heating | Bridgeport | CT |
| New England Matchplate | West Hartford | CT |
| New England Matchplate | Winchester Center | CT |
| New Haven Coliseum | New Haven | CT |
| New Haven Electric | New Haven | CT |
| New Haven Hospital | New Haven | CT |
| New Haven Hotel | New Haven | CT |
| New Haven Iron & Steel | New Haven | CT |
| New Haven Power Plant | New Haven | CT |
