| Riley's Lock | |
|---|---|
 Riley's Lock and lockhouse | |
 | |
| 39°04′09″N 77°20′27″W / 39.069167°N 77.340877°W | |
| Waterway | Chesapeake and Ohio Canal |
| Country | USA |
| State | Maryland |
| County | Montgomery |
| Operation | Defunct |
| Towpath milemarker 22.7 | |
Riley's Lock (Lock 24) and lock house are part of the 184.5-mile (296.9 km) Chesapeake and Ohio Canal (a.k.a. C&O Canal) that operated from the 1830s through 1923 along the Potomac River in the United States. They are located at towpath mile-marker 22.7, next to Seneca Creek, in Montgomery County, Maryland. The lock is sometimes identified as Seneca because of the Seneca Aqueduct that carried the canal over the creek to the lift lock. The name Riley comes from John C. Riley, who was lock keeper from 1892 until the canal closed in 1924.
The lock, lock house, and aqueduct attached to the lock were built in the early 1830s. Construction of Aqueduct 1 and other aqueducts further upriver took longer than other downriver portions of the canal, causing the first phase of canal operation to be between Georgetown and Lock 23. Completed in 1850, the canal connected Georgetown to Cumberland in Western Maryland by bypassing non-navigable portions of the Potomac River.
Today, Riley's Lock is part of Chesapeake and Ohio Canal National Historical Park. The site is the only place on the canal that has a lift lock connected to an aqueduct. Picnic tables, restrooms, parking, and a canoe ramp are on site. Ruins of the Seneca Stone Cutting Mill are less than 0.25 miles (0.40 km) away. The lock and surrounding area are known as excellent places for bird watching, and the 40-acre (16 ha) Dierssen Waterfowl Sanctuary is about two miles (3.2 km) away.