List of Classified Structures
List of Classified Structures
Return to Results Page 
Advanced Search
Record: 1  170 171 172 173 174 175 176 177 178 179 180 181 of 1343
Identification:

Preferred Structure Name:
Mile 020-021, Canal Prism
Structure Number:
020.01
Other Structure Name(s):
 
Other Structure Name(s)
No records.
Park:
Chesapeake and Ohio Canal National Historical Park
Park District:
CHOH Palisades District
Historic District:
 
Historic District
1. 
Chesapeake & Ohio Canal Historic District
Structure State:
Maryland
Structure County:
Montgomery
Region:
National Capital
Administrative Unit:
Chesapeake and Ohio Canal National Historical Park
LCS ID:
046579
 
Historical Significance:

National Register Status:
Entered - Documented
National Register Date:
08/09/1979
National Historic Landmark?:
No
Significance Level:
Contributing
Short Significance Description:
C&O Canal is a flat water canal, chartered in 1825; construction began in 1828. Prism Mile 20-21 contributes to the National Register under Criteria A & C for its architecture, engineering, commerce, transportation, conservation & military history, period of significance (1828–1924).
Long Significance Description:
The C&O Canal is a flat water canal, chartered in 1825; construction began in 1828 and by 1850 the canal was opened to its terminus at Cumberland, Maryland. The canal ceased operations in 1924 due to flood damage and the buying out of the company by the Baltimore & Ohio Railroad. In 1938, the B&O Railroad sold the canal property to the US government for $2 million dollars. The entire 184.5 miles of the canal was recognized as a National Historic Monument in 1961, and then in 1971 became known as the Chesapeake & Ohio Canal National Historical Park. Under the 1966 National Historic Preservation Act, the Canal was added to the National Register of Historic Places, having historical significance merits under architecture, engineering, commerce, transportation, military history and conservation. A confirmation National Register was approved by the Keeper for the CHOH on August 9, 1979.

The purpose of the C&O Canal was to bring freight and produce from Cumberland, Maryland, to Georgetown. The canal is an excellent example of 19th c. canal building technology. The magnitude of the engineering achievement is exemplified by the 184.5 mile length of the canal, which includes 74 lift locks rising 605 feet. Eleven stone aqueducts were constructed to carry the canal prism over large Potomac River tributaries and 241 historic culverts were built to carry smaller streams and roads under the canal. Seven supporting dams were also constructed. Among the noteworthy engineered works on the canal is the Paw Paw Tunnel, which was drilled through 3,117 feet of bedrock.
 
Construction Period:

Construction Period:
Historic
Chronology:
 
Physical Event
Begin Year
Begin Year AD/BC
End Year
End Year AD/BC
Designer
Designer Occupation
1. 
Designed
1824
AD
1828
AD

Engineer
2. 
Built
1828
AD
1831
AD

Engineer
 
Function and Use:

Primary Historic Function:
Canal
Primary Current Use:
Abandoned/Unmaintained
Structure Contains Museum Collections?:
No
Other Functions or Uses:
 
Other Function(s) or Use(s)
Historic or Current
No records.
 
Physical Description:

Structure Type:
Marine/Waterway
Volume:
2,000,000 or more cubic feet
Square Feet:
316800
Material(s):
 
Structural Component(s)
Material(s)
1. 
Superstructure
Earth
2. 
Substructure
Earth
3. 
Substructure
Stone
4. 
Superstructure
Stone
Short Physical Description:
See Long Physical Description.
Long Physical Description:
The canal prisms, constructed between 1828 and 1850, were 50-60 feet wide, with a depth of 6° feet. The prisms were hand-dug or drilled earthen trenches with a towpath on the river side and a berm to natural bedrock on the other. The bed was lined with 18-24 inches of clay. In order to prevent the sides of the prism from collapsing it was necessary, along much of the canal, to build retaining walls. Primarily built on the berm side, these walls were often of dry-laid stone or even rip-rap. Some retaining walls were also built on the towpath side in order to protect the canal from high water.

Mile 020-021, Canal Prism travels from John DuFiefs Mooring Boat Basin to the bend of the river at Blockhouse Point Park. The canal prism is approximately 60' wide at top and about 8' deep. This mile section goes through Level 22. The canal prism and towpath divided an area of two bodies of water that may have been boat basins. The towpath area was subdivided again into two basins; a berm land bridge divided the basins. Both basins were over 1,000’ in length and approximately 30’ wide. The prism continues past the basins straight to a bend in the river where it turns around a bedrock area. The prism ends at the Blockhouse Point area ,which is the base of the Seneca Break.