The Union Arch Bridge, also called the Cabin John Bridge, is a historic

masonry Masonry is the craft of building a structure with brick, stone, or similar material, including mortar plastering which are often laid in, bound, and pasted together by mortar (masonry), mortar. The term ''masonry'' can also refer to the buildin ...

structure in Cabin John,

Maryland Maryland ( ) is a U.S. state, state in the Mid-Atlantic (United States), Mid-Atlantic region of the United States. It borders the states of Virginia to its south, West Virginia to its west, Pennsylvania to its north, and Delaware to its east ...

. It was designed as part of the

Washington Aqueduct The Washington Aqueduct is an Aqueduct (water supply), aqueduct that provides the public water supply system serving Washington, D.C., and parts of its suburbs, using water from the Potomac River. One of the first major aqueduct projects in the ...

. The bridge construction began in 1857 and was completed in 1864. The roadway surface was added later. The bridge was designed by Alfred Landon Rives and built by the

United States Army Corps of Engineers The United States Army Corps of Engineers (USACE) is the military engineering branch of the United States Army. A direct reporting unit (DRU), it has three primary mission areas: Engineer Regiment, military construction, and civil wo ...

under the direction of Lieutenant

Montgomery C. Meigs Montgomery Cunningham Meigs (; May 3, 1816 – January 2, 1892) was a career United States Army officer and military and civil engineer, who served as Quartermaster General of the U.S. Army during and after the American Civil War. Although a Sou ...

. The Union Arch Bridge was designated as a

National Historic Civil Engineering Landmark __NOTOC__ The following is a list of Historic Civil Engineering Landmarks as designated by the American Society of Civil Engineers since it began the program in 1964. The designation is granted to projects, structures, and sites in the United Stat ...

by the

American Society of Civil Engineers The American Society of Civil Engineers (ASCE) is a tax-exempt professional body founded in 1852 to represent members of the civil engineering profession worldwide. Headquartered in Reston, Virginia, it is the oldest national engineering soci ...

in 1972 and was listed in the

National Register of Historic Places The National Register of Historic Places (NRHP) is the Federal government of the United States, United States federal government's official United States National Register of Historic Places listings, list of sites, buildings, structures, Hist ...

in 1973.

Bridge design

The bridge, with an overall length of and width of , is constructed of Massachusetts

granite Granite ( ) is a coarse-grained (phanerite, phaneritic) intrusive rock, intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly coo ...

and red

sandstone Sandstone is a Clastic rock#Sedimentary clastic rocks, clastic sedimentary rock composed mainly of grain size, sand-sized (0.0625 to 2 mm) silicate mineral, silicate grains, Cementation (geology), cemented together by another mineral. Sand ...

quarried at the nearby

Seneca Quarry Seneca Quarry is a historic site located at Seneca, Maryland, Seneca, Montgomery County, Maryland, Montgomery County, Maryland. It is located along the Chesapeake and Ohio Canal on the north bank of the Potomac River, just west of Seneca Cree ...

, and rises above

Cabin John Creek Cabin John Creek is a tributary stream of the Potomac River in Montgomery County, Maryland. The watershed covers an area of . The headwaters of the creek originate in the city of Rockville, and the creek flows southward for U.S. Geological Sur ...

. The main

arch An arch is a curved vertical structure spanning an open space underneath it. Arches may support the load above them, or they may perform a purely decorative role. As a decorative element, the arch dates back to the 4th millennium BC, but stru ...

span is long and rises . The bridge has an internal

spandrel A spandrel is a roughly triangular space, usually found in pairs, between the top of an arch and a rectangular frame, between the tops of two adjacent arches, or one of the four spaces between a circle within a square. They are frequently fil ...

wall structure that contains nine additional smaller arches, which are concealed from view by exterior stone sidewalls. When completed in 1864, the main span was the longest single-span masonry arch in the world. (It displaced the visually similar 1832

Grosvenor Bridge Grosvenor Bridge, originally known as, and alternatively called Victoria Railway Bridge, is a railway bridge over the River Thames in London, between Vauxhall Bridge and Chelsea Bridge. Originally constructed in 1860, and widened in 1865 and ...

Chester, England Chester is a cathedral city in Cheshire, England, on the River Dee, close to the England–Wales border. With a built-up area population of 92,760 in 2021, it is the most populous settlement in the borough of Cheshire West and Chester. It is ...

, and retained that distinction until the 1903 opening of the span of the Pont Adolphe Bridge in

Luxembourg Luxembourg, officially the Grand Duchy of Luxembourg, is a landlocked country in Western Europe. It is bordered by Belgium to the west and north, Germany to the east, and France on the south. Its capital and most populous city, Luxembour ...

.) Although Washington's population of about 58,000 was estimated to need 5,220,000 gallons per day, the conduit was designed for a daily capacity of 76,500,000 gallons. Originally, the bridge was not intended to support traffic and so the conduit was only covered with soft clay. However, soon after its completion, farmers began to use the bridge to bring produce to market. The bridge also began to be used for the transit of equipment to repair the conduit itself. "Between 1870 and 1875, a $46,000 appropriation allowed the road to have

macadam Macadam is a type of road construction pioneered by Scottish engineer John Loudon McAdam , in which crushed stone is placed in shallow, convex layers and compacted thoroughly. A binding layer of stone dust (crushed stone from the original mat ...

topping for about a mile." In the summer of 2001, the narrow roadway underwent extensive renovations, partially due to vehicles bumping and damaging the low, unreinforced stone parapet, particularly in the middle of the span where the bridge further narrows. The renovation added a pedestrian/bike lane, providing continuity for the MacArthur Boulevard Bike Trail. On the vehicle side of the roadway, a concrete curb was added to reinforce and protect the stone parapet. A low modular concrete barrier separates vehicles from pedestrians and bikes. Integrated drainage and a simple balustrade of wrought iron railing was added to both sides, protection which had not previously existed.

Controversy

The naming of the bridge has been somewhat confused, related to its completion during the

Civil War A civil war is a war between organized groups within the same Sovereign state, state (or country). The aim of one side may be to take control of the country or a region, to achieve independence for a region, or to change government policies.J ...

Union Arch inscription

While the bridge was being designed and constructed, it was referred to as "Union Arch", "Bridge No. 4" or "Cabin John Bridge" in drawings and government correspondence. The latter two names, however, do not appear in any of the stone carvings that were eventually placed on the bridge. In 1861, as the bridge was nearing completion, the Army drew up initial plans for inscription of commemorative stone tablets to be installed on the bridge. Meigs, who had been promoted to the rank of captain, issued an order in March 1861 for a tablet on the east bridge abutment. The text was to consist of a title, "Union Bridge," and the names of the principal designers, namely Meigs and Assistant Engineer Alfred L. Rives. By the time the war began, however, Rives had joined the

Confederate Army The Confederate States Army (CSA), also called the Confederate army or the Southern army, was the military land force of the Confederate States of America (commonly referred to as the Confederacy) during the American Civil War (1861–1865), fi ...

. The final tablet design was modified with the title "Union Arch" and "Alfred L. Rives" was replaced with ''"Esto Perpetua"'' ("Let it last forever."). Several publications have referred to the "Union Arch" of the Washington Aqueduct, but others refer to the structure as the Cabin John Bridge.

Jefferson Davis inscription

The bridge design process had begun in 1853, during the administration of President

Franklin Pierce Franklin Pierce (November 23, 1804October 8, 1869) was the 14th president of the United States, serving from 1853 to 1857. A northern Democratic Party (United States), Democrat who believed that the Abolitionism in the United States, abolitio ...

and the Secretary of War,

Jefferson Davis Jefferson F. Davis (June 3, 1808December 6, 1889) was an American politician who served as the only President of the Confederate States of America, president of the Confederate States from 1861 to 1865. He represented Mississippi in the Unite ...

. Captain Meigs' 1861 order also called for a tablet on the west bridge abutment, with the title, "Washington Aqueduct" and listing the political leaders that were in office both at the start of the project and at its completion (i.e., Pierce and Davis; President

Abraham Lincoln Abraham Lincoln (February 12, 1809 – April 15, 1865) was the 16th president of the United States, serving from 1861 until Assassination of Abraham Lincoln, his assassination in 1865. He led the United States through the American Civil War ...

and Secretary of War

Simon Cameron Simon Cameron (March 8, 1799June 26, 1889) was an American businessman and politician who represented Pennsylvania in the United States Senate and served as United States Secretary of War under President Abraham Lincoln at the start of the Ameri ...

). By 1862, however, Davis had left the Union to become President of the

Confederate States of America The Confederate States of America (CSA), also known as the Confederate States (C.S.), the Confederacy, or Dixieland, was an List of historical unrecognized states and dependencies, unrecognized breakaway republic in the Southern United State ...

. There was resentment among some members of

Congress A congress is a formal meeting of the representatives of different countries, constituent states, organizations, trade unions, political parties, or other groups. The term originated in Late Middle English to denote an encounter (meeting of ...

about the inscription of Davis' name on the bridge, and this led to an order that his name be removed from the tablet. The

Department of the Interior The United States Department of the Interior (DOI) is an executive department of the U.S. federal government responsible for the management and conservation of most federal lands and natural resources. It also administers programs relatin ...

, which was managing the aqueduct at that time, ordered the removal of the inscription. In 1908, President

Theodore Roosevelt Theodore Roosevelt Jr. (October 27, 1858 – January 6, 1919), also known as Teddy or T.R., was the 26th president of the United States, serving from 1901 to 1909. Roosevelt previously was involved in New York (state), New York politics, incl ...

was asked by various constituents to restore Davis' name to the tablet. Roosevelt ordered the restoration.

Twentieth century naming confusion

Some additional confusion over the bridge name arose when the

Capital Beltway The Capital Beltway, designated as Interstate 495 (I-495) for its entire length, is an List of auxiliary Interstate Highways, auxiliary Interstate Highway in the Washington metropolitan area. The Ring road, beltway encircles Washington, D.C., ...

was constructed in the early 1960s, and the nearby Beltway bridge over the

Potomac River The Potomac River () is in the Mid-Atlantic (United States), Mid-Atlantic region of the United States and flows from the Potomac Highlands in West Virginia to Chesapeake Bay in Maryland. It is long,U.S. Geological Survey. National Hydrography D ...

was also called the "Cabin John Bridge." However, in 1969 the Beltway bridge was formally named the "American Legion Memorial Bridge."

Historic designations

The Union Arch Bridge was designated as a

by the

in 1972 and was listed in the

in 1973. Both designations refer to the bridge as the "Cabin John Aqueduct."

Current operation

The bridge continues to support the

, as well as a roadway, MacArthur Boulevard. Traffic is narrowed to one lane with traffic signals controlling traffic in either direction. A concrete barrier along the south side creates a separated pedestrian walkway across the bridge. Metal fencing on both sides prevents pedestrians and objects from falling. Signs remind road maintenance crews not to salt the roadway in winter months. The U.S. Army Corps of Engineers completed a renovation of the bridge in 2001.U.S. Army Corps of Engineers, Baltimore, M
"Constellation" (Newsletter), Vol. 21, No. 12.
Page 5. December 2001.

References

External links

* * *, including photo in 2003, at Maryland Historical Trust website
American Society of Civil Engineers – Cabin John Aqueduct
* {{Authority control Bridges completed in 1864 Cabin John, Maryland Road bridges on the National Register of Historic Places in Maryland Historic Civil Engineering Landmarks Bridges in Montgomery County, Maryland Historic American Engineering Record in Maryland Historic American Buildings Survey in Maryland National Register of Historic Places in Montgomery County, Maryland Stone arch bridges in the United States