Connecticut - Criteria: A (event)
| Pequot Fort |
| Perkins-Bill House |
| Perry Avenue Bridge |
| Phelps, Arah, Inn |
| Phelps, Eli, House |
| Phelps Farms Historic District |
| Phoenix Life Insurance Company Building |
| Pine Grove Historic District |
| Pine Meadow Historic District |
| Pines Bridge Historic District |
| Pinney, David, House and Barn |
| Pistol Factory Dwelling |
| Pitkin Glassworks Ruin |
| Plainfield Street Historic District |
| Plainfield Woolen Company Mill |
| Plant, Morton Freeman, Hunting Lodge |
| Pledger, Jacob, House |
| Polish National Home |
| Pomeroy, Arthur G., House |
| Pomfret Street Historic District |
| Pomfret Town House |
| Pond-Weed House |
| Poquetanuck Village Historic District |
| Portland Brownstone Quarries |
| Post, Augustus, House |
| Post Hill Historic District |
| Pratt, Read and Company Factory Complex |
| Pratt Street Historic District |
| Preston City Historic District |
| Prospect Avenue Historic District |
| Prospect Green Historic District |
| Prospect Hill Historic District |
| Prospect Street Historic District |
| Pultz & Walkley Company |
| Putnam High School |
| Putnam, Israel, Wolf Den |
| Putnam Memorial State Park |
| Putnam Railroad Station |
| Quaker Hill Historic District |
| Quinebaug Mill-Quebec Square Historic District |
| Quinebaug River Prehistoric Archeological District |
| Quinnipiac Brewery |
| Quinnipiac River Historic District |
| Railroad Avenue Industrial District |
| Ramsdell, Hezekiah S., Farm Site |
| Rapallo Viaduct |
| Red Bridge |
| Red Mountain Shelter |
| Remington City Historic District |
| Revolutionary War Campsite |
| Revonah Manor Historic District |
| Reynolds Bridge |
| Rising Sun Tavern |
| River Park Historic District |
| River Road-Mead Avenue Historic District |
| River Road Stone Arch Railroad Bridge |
| Riverside Avenue Bridge |
| River Street Historic District |
| Riverton Historic District |
| Robbins, Unni II, House |
| Robinson, P., Fur Cutting Company |
| Rock Hall |
| Rockville Historic District |
| Rockwell Park |
| Rocky Hill Center Historic District |
| Rogers, John, House |
| Rosemary Hall |
| Round Hill Historic District |
| Route 146 Historic District |
| Roxbury Center |
| Roxbury Iron Mine and Furnace Complex |
| Russell Company Upper Mill |
| Russian Village Historic District |
| Rye House |
| Sabbathday House |
| SABINO (steamer) |
| Sage-Kirby House |
| Saint Anthony Hall |
| Saint Luke's Home for Destitute and Aged Women |
| Salem School |
| Sanford Road Historic District |
| Saugatuck River Bridge |
| Saugatuck River Railroad Bridge |
| Saxony Mill |
| Saybrook Breakwater Lighthouse |
| Schlaraffia Burg |
| Schoverling, Carl F., Tobacco Warehouse |
| Scoville Memorial Library |
| Seaside Institute |
| Seaside Park |
| Seaside Village Historic District |
| Second Church of Christ |
| Selleck, Sylvanus, Gristmill |
| Seymour, Elisha, Jr., House |
| Seymour High School and Annex |
| Shade Swamp Shelter |
| Sharon Historic District |
| Sharon Valley Historic District |
| Sharpe's Trout Hatchery Site |
| Shaw Mansion |
Data from United States Park Service and Wikidata
