| distance | reference number | name | latitude | longitude |
| 270.3 | 1825 | Middle Branch, Patapsco River, Baltimore Harbor, Ma | 39.2667 | -76.6333 |
| 271.0 | 969 | Fells Point, Baltimore Harbor, Maryland | 39.2833 | -76.5833 |
| 271.9 | 2369 | Port Deposit, Susquehanna River, Maryland | 39.6 | -76.1167 |
| 272.0 | 137 | Baltimore (Fort McHenry), Maryland | 39.2667 | -76.5783 |
| 274.5 | 503 | Chain Bridge, Washington, D.C. | 38.9333 | -77.1167 |
| 275.8 | 502 | Chain Bridge, one mile below, Washington, D.C. | 38.9167 | -77.1 |
| 275.9 | 1245 | Havre de Grace, Chesapeake Bay, Maryland | 39.5367 | -76.09 |
| 275.9 | 1246 | Havre de Grace, Maryland | 39.5367 | -76.09 |
| 276.4 | 1251 | Hawkins Point, Patapsco River, Maryland | 39.2083 | -76.5333 |
| 276.5 | 1019 | Fort Carroll, Patapsco River, Maryland | 39.2167 | -76.5167 |
| 276.8 | 319 | Bowley Bar, Middle River, Maryland | 39.3 | -76.3833 |
| 276.8 | 172 | Battery Point, Gunpowder River, Maryland | 39.3333 | -76.3333 |
| 276.9 | 2339 | Pond Point, Bush River, Maryland | 39.3883 | -76.255 |
| 277.5 | 1495 | Key Bridge, Washington, D.C. | 38.9 | -77.0667 |
| 277.8 | 991 | Fishing Battery Light, Susquehanna River, Maryland | 39.5 | -76.0833 |
| 278.7 | 2574 | Rocky Point, Back River, Maryland | 39.25 | -76.4 |
| 279.0 | 273 | Bladensburg, Anacostia River, Maryland | 38.9333 | -76.9383 |
| 279.2 | 520 | Charlestown, Northeast River, Maryland | 39.5667 | -75.9667 |
| 279.5 | 2042 | North Point, Patapsco River, Maryland | 39.2 | -76.45 |
| 280.1 | 233 | Benning Bridge, Anacostia River, Washington, D.C. | 38.9 | -76.9667 |
| 280.1 | 3268 | Washington, Potomac River, D.C. | 38.8733 | -77.0217 |
| 281.0 | 59 | Anacostia Bridge, Anacostia River, Washington, D.C. | 38.8667 | -77 |
| 281.1 | 2509 | Reagan National Airport, Washington, D.C. | 38.85 | -77.0333 |
| 281.6 | 2341 | Pooles Island, Susquehanna River, Maryland | 39.2833 | -76.2667 |
| 282.0 | 222 | Bellevue, Washington, D.C. | 38.8333 | -77.0333 |