thumb|256px|View of the causeway, facing east (Bahraini side)
The King Fahd Causeway () is a 25 km (15.5 mi) long series of bridges and causeways connecting Khobar, Saudi Arabia, and Al Jasra, Bahrain across the Gulf of Bahrain.
Its five bridges rest on 536 concrete pylons, with seven embankments in the gulf's shallower water.
In 1965, plans to construct the causeway began to take form officially when Sheikh Khalifah ibn Sulman Al Khalifah, the prime minister of Bahrain, paid a courtesy visit to King Faisal at which time the king again expressed his wish to move forward. This was to bring it into line with neighbouring countries.
In 1968, a joint committee was formed to assess the finances required for undertaking the task. As a result, the committee requested the World Bank contribute assistance to implement the mammoth-sized project including environmental and geographical aspects of the region.
In the summer of 1973, King Faisal, in a meeting which included Emir Sheikh Isa bin Salman Al Khalifa as well as Prince Fahd bin Abdulaziz and Sheikh Khalifa bin Salman Al Khalifa, suggested the committee ignore economic and financial issues with the project, and instead concentrate on the actual construction.
The Saudi–led intervention in Bahrain, which used the causeway to cross over into Bahrain with 150 vehicles, began on 14 March 2011 to assist the Bahraini government in suppressing an anti-government uprising in the country. The intervention came three weeks after the U.S. pressured Bahrain to withdraw its military forces from the streets. As a decision by the Gulf Cooperation Council (GCC), the intervention included sending 1,000 (1,200)
Construction details
The project cost a total of US$800 million (SAR3 billion). Al-Muhandis Nizar Kurdi Consulting Engineers was the sole Saudi partner of the consulting group (Saudi Danish Consultants) which completed the study, design and construction supervision of the causeway. One of the major contractors of the project was Ballast Nedam, based in the Netherlands. It is unclear how many workers were engaged in the construction of the causeway. The four-lane road is long and its two roadways are wide. The Saudi side of the border station has outlets of McDonald's and Kudu while the Bahraini side of the border station has a McDonald's outlet.
thumb|250px|The bridge leading to mainland Bahrain
One-stop crossing was introduced on the King Fahd Causeway from 6 March 2017. Under the new system, commuters will only have to stop at one post for passport control, car clearance and customs. The measure will ease travel for commuters and is also expected to ease traffic congestion on the highway, as the previous system required stops at both Saudi and Bahraini check posts.
Expansion
On 6 July 2010, Saudi newspapers quoted King Fahd Causeway Authority chief Bader Abdullah Al-Otaishan as saying that the King Fahd Causeway was to undergo a major expansion projected to cost $5.3 million. It was announced that the number of departure lanes would be increased from 10 to 17 and the number of arrival lanes from 13 to 18 on both sides. The renovation includes construction of a commercial centre on the Bahraini side.