Editing Covered bridge (section)

=== North America ===
{{main|List of lists of covered bridges in North America}}Most bridges were built to cross streams, and the majority had just a single [[Span (engineering)|span]]. Virtually all contained a single lane. A few two-lane bridges were built, having a third, central truss.<ref name="DOT" />

Many different truss designs were used. One of the most popular designs was the [[Burr Truss]], patented in 1817, which used an arch to bear the load, while the trusses kept the bridge rigid. Other designs included the [[King post|King]], [[Queen post|Queen]], [[Lattice truss bridge|Lattice]], and [[Howe truss]]es.

Early trusses were designed with only a rough understanding of the engineering dynamics at work.<ref name="brit-timber" /> In 1847, American engineer [[Squire Whipple]] published the first correct analysis of the precise ways that a load is carried through the components of a truss,<ref>{{cite book|last1=Allen|first1=Richard Sanders|title=Covered Bridges of the Northeast|date=2004|publisher=Courier Corporation|isbn=978-0-486-43662-3|page=84}}</ref> which enabled him to design stronger bridges with fewer materials.

====United States====
[[File:Schuylkill Permanent Bridge at High Street, the first covered bridge in America.jpg|thumb|Schuylkill Permanent Bridge in Philadelphia, the first documented covered bridge in America]]
About 14,000 covered bridges have been built in the United States,<ref name="fhwa-manual">{{cite book |title=Covered Bridge Manual (PUBLICATION NO. FHWA-HRT-04-098) |date=April 2005 |publisher=U. S. Department of Transportation Federal Highway Administration |location=McLean, VA |page=3 |url=https://www.fhwa.dot.gov/publications/research/infrastructure/structures/04098/04098.pdf |access-date=27 February 2020}}</ref> mostly in the years 1825 to 1875.<ref name="fhwa-ohio" /> The first documented was the [[Market_Street_Bridge_(Philadelphia)#First_bridge_-_Schuylkill_Permanent_Bridge|''Permanent Bridge'']], completed in 1805 to span the [[Schuylkill River]] in [[Philadelphia]].<ref name="structuremag2013">{{cite web |url=https://www.structuremag.org/?p=817 |title=The Permanent Bridge |work=Structure Magazine |last1=Griggs |first1=Frank Jr. |date=October 2013 |access-date=9 January 2019}}</ref><ref>Christianson, Justine, et al. [https://web.archive.org/web/20170127175019/https://www.nps.gov/HDP/CoveredBridges2015med.pdf ''Covered Bridges and the Birth of American Engineering'']. Washington, D.C.: National Park Service, Historic American Engineering Record, 2015.</ref> However, most other early examples of covered bridges do not appear until the 1820s. Extant bridges from that decade include [[New York (state)|New York]]'s  [[Hyde Hall Bridge]] and [[Pennsylvania]]'s [[Hassenplug Bridge]], both built in 1825, and the [[Haverhill–Bath Covered Bridge]] and the [[Roberts Covered Bridge]], in [[New Hampshire]] and  [[Ohio]] respectively, both built in 1829.<ref name="DOT" />
[[File:Fifth Street (covered) bridge, entrance, circa 1877 - DPLA - d729e9efdd48d34d1fce20fb80c6bd89.jpeg|thumb|Covered bridge in Macon, Georgia, 1877]]
The longest covered bridge ever built was constructed in 1814 in [[Lancaster County, Pennsylvania|Lancaster County]], Pennsylvania, and spanned over a mile in length, but was destroyed by ice and flooding in 1832.<ref name="usdot-fha_ohio">{{cite web |title=Ohio's Vanishing Covered Bridges - Back in Time - General Highway History - Highway History - Federal Highway Administration |url=https://www.fhwa.dot.gov/infrastructure/back0804.cfm |website=[[Federal Highway Administration|Federal Highway Administration (FHWA)]] |publisher=USDOT Federal Highway Administration |access-date=4 March 2021}}</ref> The longest, historical covered bridges remaining in the United States are the [[Cornish–Windsor Covered Bridge|Cornish–Windsor Bridge]], spanning the Connecticut River between New Hampshire and Vermont, and [[Medora Covered Bridge|Medora Bridge]], spanning the East Fork of the White River in Indiana. Both lay some claim to the superlative depending upon how the length is measured.<ref>{{cite web |title=Covered Bridge Trivia |url=http://www.coveredbridgesociety.org/cb-faq.html |website=www.coveredbridgesociety.org |publisher=National Society for the Preservation of Covered Bridges |access-date=27 February 2020}}</ref><ref name=":0">{{Cite web |last=Brady |first=Matthew |date=2023-07-17 |title=Bridging the Past and Present |url=https://americanlifestylemag.com/life-culture/travel/bridging-the-past-and-present/ |access-date=2023-08-20 |website=American Lifestyle Magazine |language=en-US}}</ref>

In the mid-19th century, the use of cheaper [[wrought iron]] and [[cast iron]] led to metal rather than timber trusses.<ref name="DOT">{{cite web |url=https://www.fhwa.dot.gov/publications/research/infrastructure/structures/04098/ |title=Covered Bridge Manual |publisher=Federal Highway Administration |access-date=9 October 2012}}</ref> Metal structures did not need protection from the elements, so they no longer needed to be covered. The bridges also became obsolete because most were single-lane, had low width and height clearances, and could not support the heavy loads of modern traffic.<ref name="DOT" />

{{As of|2004}}, there were about 750 left,<ref name="conwill">{{cite book|last1=Conwill|first1=Joseph D.|title=Covered bridges across North America|date=2004|publisher=MBI Pub. Co|isbn=0-7603-1822-0|location=St. Paul, Minn.}}</ref> mostly in eastern and northern states. The 2021 [[World Guide to Covered Bridges]] lists 840 covered bridges in the U.S., although it states that only 670 of those were standing when the 1959 edition was published.<ref>{{cite book |last1=Caswell |first1=William S. |title=World Guide to Covered Bridges |date=31 October 2021 |publisher=National Society for the Preservation of Covered Bridges |location=Concord, New Hampshire |isbn=978-0-578-30263-8 |pages=xii |edition=2021}}</ref> The tallest (35 feet high), built in 1892, is the [[Felton Covered Bridge]], just north of [[Santa Cruz, California]].<ref name=":0" />

==== Canada ====
Between 1969 and 2015, the number of surviving covered bridges in Canada declined from about 400 to under 200.<ref>{{cite web |url=https://www.canadiangeographic.ca/article/throwback-thursday-covered-bridges |title=Throwback Thursday: Covered bridges |website=Canadian Geographic |last1=Walker |first1=Nick |date=28 May 2015 |access-date=8 January 2019}}</ref>

In 1900, [[List of covered bridges in Quebec|Quebec]] had an estimated 1,000 covered bridges.<ref>{{cite web |url=http://www.mtq.gouv.qc.ca/portal/page/portal/grand_public/vehicules_promenade/reseau_routier/structures/ponts_couverts |title=Ponts couverts |publisher=Transports Quebec |language=fr-CA |archive-url=https://web.archive.org/web/20120224014629/http://www.mtq.gouv.qc.ca/portal/page/portal/grand_public/vehicules_promenade/reseau_routier/structures/ponts_couverts |archive-date=24 February 2012 |url-status=dead}}</ref> Relative to the rest of North America, Quebec was late in building covered bridges, with the busiest decade for construction being the 1930s.<ref name="quebec">{{cite web |url=http://conf.tac-atc.ca/english/resourcecentre/readingroom/conference/conf2004/docs/s10/francois.pdf |title=Les ponts couverts au Québec, héritage précieux |publisher=Ministère des Transports du Québec |language=fr-CA |last1=Lefrançois |first1=Jean |date=2004 |access-date=8 January 2019}}</ref> Initially, the designs were varied, but around 1905, the design was standardised to the ''Town québécois'', a variant on the [[Lattice truss bridge|lattice]] truss patented by [[Ithiel Town]] in 1820. The designer is unknown. About 500 of these were built in the first half of the 20th century.<ref name="quebec" /> They were often built by local settlers using local materials, according to standard plans.<ref name="conwill" /> The last agricultural colony was founded in 1948, and the last bridge was built by the Ministry of Colonisation in 1958 in [[Lebel-sur-Quévillon]].<ref name="quebec" /> There are now 82 covered bridges in Quebec, [[Transports Québec]] including the [[Félix-Gabriel-Marchand Bridge]], the province's longest covered bridge.<ref>{{Cite web |url=https://www.transports.gouv.qc.ca/fr/salle-de-presse/nouvelles/Pages/programmation-routiere-2018-2020-outaouais.aspx?rev=636825413055456545 |title=Programmation routière 2018-2020 - Plus de 157 M$ pour améliorer la sécurité et la qualité de vie des usagers de la route en Outaouais |publisher=Transports Québec |language=fr-CA |date=5 March 2018 |access-date=8 January 2019 |archive-date=19 September 2020 |archive-url=https://web.archive.org/web/20200919215232/https://www.transports.gouv.qc.ca/fr/salle-de-presse/nouvelles/Pages/programmation-routiere-2018-2020-outaouais.aspx?rev=636825413055456545 |url-status=dead }}</ref> In Quebec covered bridges were sometimes known as ''pont rouges'' (red bridges) because of their typical colour.<ref name="conwill" />{{rp|11, 87}}

Like Quebec, [[New Brunswick]] continued to build covered bridges into the 1950s, peaking at about 400 covered bridges. These mostly used the Howe, Town, and Burr trusses. Today, there are [[List of covered bridges in New Brunswick|58 covered bridges in New Brunswick]], including the world's longest, the [[Hartland Bridge]].<ref>{{cite web |url=https://www2.gnb.ca/content/gnb/en/departments/dti/bridges_ferries/content/covered_bridges.html |title=Covered Bridges |date=7 October 2011 |publisher=Government of New Brunswick |access-date=11 July 2019}}</ref> 

Ontario has just two remaining covered bridges, the [[West Montrose Covered Bridge]] and the very short [[Latchford, Ontario#Bridges|covered bridge in Latchford]].