Connecticut - Criteria: A (event)
| Mixer Tavern |
| Monroe Center Historic District |
| Montauk Avenue Historic District |
| Moody, Dr. Mary B., House |
| Moore, Edward and Ann, House |
| Moore Jr., William, House |
| Morris Cove Historic District |
| Mory's |
| Mount Riga Ironworks Site |
| Mount St. Joseph Academy |
| Mount Tom Tower |
| Municipal Building |
| Murphy, Charles and Peggy House |
| Murphy, Patrick, House |
| Music Mountain |
| Mystic Bridge Historic District |
| Mystic River Historic District |
| Nathaniel Wheeler Memorial Fountain |
| Nathaniel Witherell Historic District |
| National Hall Historic District |
| Naubuc Avenue-Broad Street Historic District |
| Naugatuck Center Historic District |
| New Britain Public High School Campus |
| New England Hebrew Farmers of the Emanuel Society Synagogue and Creamery Site |
| New Haven Clock Company Factory |
| New Haven County Courthouse |
| New Haven District Campground |
| New Haven Jewish Home for the Aged |
| New Haven Lawn Club |
| New Haven Railroad Danbury Turntable |
| New Haven Railroad Station |
| Newington Junction Railroad Depot |
| New London County Courthouse |
| New London Harbor Lighthouse |
| New London Ledge Lighthouse |
| New London Railroad Station |
| New Milford Center Historic District |
| New Preston Hill Historic District |
| New Roxbury Ironworks Site |
| Newtown Borough Historic District |
| Nichols Satinet Mill Site |
| Nicoll, Caroline, House |
| Ninth Square Historic District |
| Noank Historic District |
| Norcross Brothers Granite Quarry |
| Norfield Historic District |
| North Branford Center Historic District |
| North Cove Historic District |
| Northfield Knife Company Site |
| Northford Center |
| North Grosvenordale Mill Historic Disrict |
| North Stonington Village Historic District |
| North-West School |
| Norton House |
| Norwalk City Hall |
| Norwalk Island Lighthouse |
| Norwalk River Railroad Bridge |
| Norwich Hospital District |
| Norwich Town Hall |
| Noyes, William, Farmstead |
| Oak Lodge |
| Occum Hydroelectric Plant and Dam |
| O'Connell, Clara T., School |
| Ogden, David, House |
| Old Farm Schoolhouse |
| Old Lyme Historic District |
| Old Middletown High School |
| Old Mine Park Archeological Site |
| Old Newgate Prison |
| Old North Cemetery |
| Old Riverton Inn |
| Old Rockville High School and East School |
| Old Saybrook South Green |
| Old Town Hall |
| Old Town Hall |
| Old Westfield Cemetery |
| Old Wethersfield Historic District |
| Oliver White Tavern |
| Orange Street Historic District |
| Overlook Historic District |
| Oxford-Whitney Streets Historic District |
| Oyster Point Historic District |
| Palace and Majestic Theaters |
| Palisado Avenue Historic District |
| Palmer, Capt. Nathaniel B., House |
| Palmer, Hezekiah, House |
| Palmer, Isaac, House |
| Park Apartments |
| Parker-Hutchinson Farm |
| Parkville Historic District |
| Park, William, House |
| Parmelee House |
| Paugnut Forest Administration Building |
| Payne, Daniel, House |
| Peck Ledge Lighthouse |
| Peck Tavern |
| Penfield Reef Lighthouse |
| Peoples Forest Museum |
| Pequabuck Bridge |
| Pequonnock River Railroad Bridge |
Data from United States Park Service and Wikidata
