Maritime chokepoint closures

With the Berlin Decree of 21 November 1806, Napoleon I instituted the Continental System, a large-scale embargo closing the ports of France, its allies and satellites to British trade, intended to asphyxiate the British economy in response to Britain's naval blockade of the French coasts enacted on 16 May 1806. Britain answered with the Orders in Council of 1807 and a counter-blockade of continental ports. Enforcement proved porous: smuggling flourished, often with the connivance of Napoleon's client rulers, and Britain redirected exports to markets in the rest of the world. The system also hurt the continental economies it was meant to protect, and Russia's reopening of trade with Britain in 1810 — its withdrawal from the system — was a motivating factor behind Napoleon's decision to invade Russia in 1812. Applied intermittently, the embargo collapsed with the defeat of the French Empire and ended on 11 April 1814, after Napoleon's first abdication.

Outcome: The blockade collapsed with Napoleon's military defeat and ended on 11 April 1814 after his first abdication; Britain, its target, outlasted it while the loss of British trade damaged the economies of France and its allies.

• •The British economy suffered most acutely in 1810–12, with high unemployment and inflation contributing to unrest including the Luddite movement, but sharply increased trade with the rest of the world covered much of the decline in continental exports.^[1]
• •The loss of British trade hit the economies of France and its allies, and extensive smuggling of British goods — often with the connivance of Napoleon's client rulers — made the embargo ineffective; Russia reopened trade with Britain in 1810, and its withdrawal from the system was a motivating factor behind Napoleon's decision to invade Russia in 1812.^[1]
• •The system damaged continental regions dependent on overseas commerce even as it stimulated manufacturing in parts of France, and Napoleon's efforts to halt evasions of his blockade stretched French forces too thin, ultimately provoking his calamitous invasion of Russia in 1812.^[2]

No price series covers this era — event facts and sources only.

On 19 April 1861, President Abraham Lincoln proclaimed a naval blockade of the ports of the seceded Southern states, extending it to Virginia and North Carolina on 27 April. Executed as part of the Anaconda Plan, the blockade aimed to isolate the Confederacy economically and diplomatically by cutting cotton exports and imports of weapons and supplies. Blockade runners slipped through frequently early in the war, but the Union navy's effectiveness rose steadily as it expanded and captured Southern ports, and the small, fast runners that survived could carry little heavy cargo. The collapse of cotton exports — driven by the blockade together with the South's own informal early-war cotton embargo — starved the Confederacy of foreign exchange and wrecked its currency. The blockade outlasted the Confederacy and was formally lifted by President Andrew Johnson's proclamation of 23 June 1865.

Outcome: The blockade was maintained until the Confederacy's collapse and was formally lifted by President Johnson's proclamation of 23 June 1865 — the blockading power prevailed.

• •Cotton exports to Europe collapsed from about 3.8 million bales in 1860 to virtually nothing in 1862 — a drop produced by the blockade in combination with the Confederacy's own informal embargo on cotton exports.^[7]
• •Interception rates against blockade runners rose from roughly one in ten ships early in the war to about one in three by 1864.^[6]

During the Italo-Turkish War, an Italian naval demonstration against the Dardanelles on 16–19 April 1912 — including a bombardment of the outer forts on 18 April — prompted the Ottoman government to close and mine the straits entirely, halting merchant traffic between the Black Sea and the Mediterranean. The closure stranded shipping — much of it British, with some 185 vessels reported unable to move — and cut off Russian grain exports, provoking a Russian protest on 20 April and complaints from the other trading powers; the matter was debated in the British House of Lords on 2 May 1912 while the straits were still shut. Bowing to intense international pressure, the Ottomans reopened the straits to merchant shipping in May 1912 after a closure lasting roughly a month (reported reopening dates range from 10 to 19 May). The episode exposed Russia's acute economic dependence on the straits shortly before the Balkan Wars and the First World War.

Outcome: The Ottomans backed down under intense great-power diplomatic pressure, reopening the straits to merchant shipping in May 1912 after a closure of roughly a month (reported reopening dates range from 10 to 19 May).

• •McMeekin: the volume of Russia's Black Sea exports dropped by one-third for calendar year 1912, and export revenue dipped 30 percent, from £77 million (nearly 800 million rubles) to £57 million.^[2]
• •British shipping was heavily exposed: of the 15.75 million tons of shipping arriving at Constantinople in 1909, 6.75 million tons were British, and the closure stranded merchant vessels awaiting passage — some 185 vessels were reported unable to move in the House of Lords debate of 2 May 1912.^[1]

On 27 September 1914 the Ottoman Empire closed the Dardanelles to British, French and Russian shipping, extinguishing lighthouses and laying minefields across the narrows; the closure became total as the empire entered the First World War on the side of the Central Powers in late October 1914, shutting the waterway to all commercial traffic. The closure severed Russia's principal export and import artery between the Black Sea and the Mediterranean at a time when the Baltic was controlled by Germany, cutting off Russian and Romanian grain shipments and Allied supply routes. The Allied attempt to force the straits at Gallipoli in 1915 failed with heavy losses, and the waterway remained shut to Allied commerce until the Armistice of Mudros on 30 October 1918 provided for its opening and Allied passage.

Outcome: The straits stayed closed for the entire war — the Gallipoli attempt to force them failed — and reopened only with the Ottoman surrender at Mudros on 30 October 1918, which provided for Allied passage and occupation of the strait forts.

• •In the five-year period immediately before the war roughly a third of the global wheat supply came from the Black Sea, and the closure of the Dardanelles was the single most important factor driving up world wheat prices; neutral importers such as Greece, Spain and Italy, which had bought most of their wheat from Russia, were forced to seek grain in the Americas and compete there with Entente buyers.^[3]
• •With the Baltic Sea already under German control, the Ottoman blockade of the Black Sea exit interrupted Russia's maritime links with its allies; agricultural products had made up 63 per cent of Russian exports in 1913, and a large part of agricultural production was exported to cover industrial imports and debt.^[2]

After Egypt nationalized the Suez Canal in July 1956, the United Kingdom, France and Israel attacked Egypt in late October and November 1956. In response, Egypt blocked the waterway by sinking dozens of vessels — dredgers, tugs, floating cranes and other craft — at Port Said and along the canal. The canal remained impassable for about five months, severing the route that carried roughly two-thirds of the oil consumed in Europe and prompting petrol rationing in Britain. Under United Nations auspices, a salvage fleet raised the wrecks, and the canal reopened to shipping in April 1957 under full Egyptian control, with Egypt's nationalization of the canal left standing.

Outcome: The invading powers withdrew under American, Soviet and UN pressure; a UN salvage fleet cleared the wrecks and the canal reopened in April 1957 under full Egyptian control, with the nationalization intact.

• •Around 67% of the oil consumed in Europe at the time came through the Suez Canal, mostly from Arab states.^[1]
• •Egypt sank 47 vessels (a frigate, dredgers, tugs, floating cranes and docks, hoppers and salvage craft) to block the canal.^[3]
• •A UN-organized salvage fleet raised roughly 40 sunken ships before navigation could resume.^[5]
• •Petrol rationing was introduced in the United Kingdom in December 1956 and lasted until May 1957.^[2]

Egypt, then officially the United Arab Republic, closed the Suez Canal on 6 June 1967 during the Six-Day War, blocking it with mines, sunken vessels and debris as the east bank became the front line with Israeli forces occupying Sinai. The canal remained shut for eight years, the longest closure in its history, trapping fourteen foreign cargo ships — the 'Yellow Fleet' — in the Great Bitter Lake, where their crews founded the Great Bitter Lake Association. Shipping between Europe and Asia was forced around the Cape of Good Hope for nearly a decade. After the 1973 war, Egyptian–Israeli disengagement accords and an internationally assisted clearance of mines and wrecks, Egypt reopened the canal on 5 June 1975.

Outcome: The canal reopened on 5 June 1975 after the 1973 war and Egyptian–Israeli disengagement accords enabled an internationally assisted mine- and wreck-clearance, with Egypt reopening the waterway it had closed.

• •In 1966, 60% of Italy's, 39% of France's and 25% of the United Kingdom's total oil consumption passed through the Suez Canal.^[1]
• •Fourteen foreign cargo ships from eight countries (the 'Yellow Fleet') were trapped in the Great Bitter Lake for the full eight years of the closure.^[2]
• •Feyrer (NBER, 2009) used the closure as a natural experiment and estimated that the resulting increases in ocean shipping distances significantly reduced bilateral trade for affected country pairs.^[3]

On 22 May 1967, President Gamal Abdel Nasser of the United Arab Republic announced that the Straits of Tiran would be closed to all ships flying Israeli flags or carrying strategic materials, effective 23 May, cutting Israel's only maritime access from the Red Sea to the port of Eilat. Egypt also announced, falsely, that the straits had been mined. Israel had stated since 1957 that a renewed closure of the straits would constitute a casus belli. On 5 June 1967 Israel launched the Six-Day War with airstrikes on Egyptian airfields; Israeli forces captured Sharm el-Sheikh on 7 June, breaking the blockade, and Defense Minister Moshe Dayan declared the straits an international waterway open to all shipping without restriction.

Outcome: Israel went to war and captured Sharm el-Sheikh on 7 June 1967, breaking the blockade by force and declaring the straits open to all shipping.

• •An estimated 90% of Israel's oil passed through the Straits of Tiran at the time of the blockade.^[2]
• •Israel had declared since 1957 that renewed closure of the straits would be treated as a casus belli; the blockade was a proximate trigger of the war launched on 5 June 1967.^[1]

During the Iran–Iraq War, both belligerents attacked merchant shipping in the Persian Gulf. From 1984 Iraq escalated strikes on tankers serving Iran's Kharg Island oil terminal, aiming to strangle Iranian oil exports and, by provoking Iranian retaliation such as a closure of the Strait of Hormuz, to draw in foreign intervention; Iran retaliated against ships trading with Iraq's Gulf backers, chiefly Kuwait and Saudi Arabia. Attacks concentrated around the Strait of Hormuz and Gulf shipping lanes but never closed the strait. After Kuwait sought protection in December 1986, the United States reflagged eleven Kuwaiti tankers and escorted convoys under Operation Earnest Will from July 1987. Attacks on shipping ended with the UN-brokered Iran–Iraq ceasefire that took effect on 20 August 1988.

Outcome: Attacks on Gulf shipping ended with the UN-brokered Iran–Iraq ceasefire of 20 August 1988; the strait was never fully closed, and US convoy escorts concluded in September 1988.

• •451 attacks on ships were recorded — 283 attributed to Iraq and 168 to Iran, according to a May 1988 US Naval Institute Proceedings tally.^[2]
• •Well over 100 sailors were killed and a similar number wounded, and more than 30 million tons of cargo was damaged from 1981 to 1987.^[2]
• •Only 55 of the 239 petroleum tankers attacked (23 percent) were completely sunk or declared constructive total losses, and the attacks failed to disrupt more than two percent of ships passing through the Persian Gulf.^[4]
• •Eleven Kuwaiti tankers were reflagged under the US flag after Kuwait accepted a 7 March 1987 US offer of reflagging and US Navy protection, with escorts beginning in July 1987.^[6]
• •Operation Earnest Will (24 July 1987 – 26 September 1988), the US Navy escort of the reflagged Kuwaiti tankers, was the largest naval convoy operation since World War II.^[3]

Amid heightened tensions after the US withdrawal from the Iran nuclear deal, a series of tanker incidents disrupted Gulf shipping in mid-2019. On 4 July 2019, authorities in Gibraltar, supported by British Royal Marines, seized the Iranian tanker Grace 1 on suspicion of carrying oil to Syria in violation of EU sanctions. On 19 July, Iran's Revolutionary Guard seized the UK-flagged tanker Stena Impero in the Strait of Hormuz for alleged marine violations, a move widely viewed as retaliation. Gibraltar released the Grace 1 on 15 August after receiving Iranian assurances that its cargo would not go to Syria; Iran declared the Stena Impero free to leave on 23 September, and the ship departed Bandar Abbas for Dubai on 27 September 2019. The strait remained open to general traffic throughout.

Outcome: The confrontation de-escalated through reciprocal releases — Gibraltar freed the Grace 1 on 15 August and Iran released the Stena Impero on 27 September 2019 — with the strait open throughout.

• •Gibraltar authorities seized the Iranian tanker Grace 1 on 4 July 2019 on suspicion of shipping oil to Syria in breach of EU sanctions and released it on 15 August after Iranian assurances; the renamed Adrian Darya 1 was later photographed near the Syrian port of Tartus.^[2]
• •The UK-flagged Stena Impero was held for more than two months (19 July – 27 September 2019) before leaving Bandar Abbas for Port Rashid, Dubai.^[1]

On 23 March 2021, the Panama-flagged container ship Ever Given, operated by Evergreen Marine with a capacity of about 20,000 TEU, ran aground diagonally across the southern section of the Suez Canal after strong winds and limited visibility caused it to veer off course, completely blocking the waterway in both directions. The obstruction halted all canal traffic for six days and built a large queue of waiting vessels while some carriers diverted around the Cape of Good Hope. Working with dredgers, tugboats and the Dutch salvage firm SMIT, the Suez Canal Authority refloated the vessel on 29 March 2021, and transit through the canal resumed. Egypt subsequently detained the ship until a compensation settlement was reached with its owners.

Outcome: The Suez Canal Authority and SMIT Salvage refloated the Ever Given on 29 March 2021 after six days and traffic resumed immediately — an accidental blockage cleared by physical salvage effort.

• •Lloyd's List estimated the blockage was holding up about $9.6 billion of trade per day.^[2]
• •The canal was blocked for six days (23–29 March 2021) before the Suez Canal Authority, assisted by SMIT Salvage, refloated the vessel and traffic resumed.^[1]

A prolonged drought over the Panama Canal watershed, intensified by a strong El Niño, drove Gatún Lake to its lowest levels since at least 1965. Because the locks release fresh water from the lake with each transit, the Panama Canal Authority imposed progressively tighter restrictions rather than closing the waterway: maximum drafts were cut through the first half of 2023 (container vessels from the normal 50 feet to 44 feet) and daily transits were capped at an average of 32 from 30 July 2023, tightening to a low of 22 booking slots per day in December 2023. The squeeze produced long queues (more than 160 vessels waiting in August 2023, with waits of 17+ days for Neopanamax-size ships) and cargo diversions via the Suez Canal and the Cape of Good Hope, with significant effects on US grain, energy and container trade. Above-average rains from November 2023 let the authority cancel planned deeper cuts and raise slots step by step, and the full complement of 36 daily booking slots was restored for booking dates from 1 September 2024.

Outcome: Rainfall recovery allowed the Panama Canal Authority to phase out its own restrictions: the Neopanamax draft limit returned to 50 feet on 16 August 2024, and 36 daily booking slots were restored for booking dates from 1 September 2024.

• •The Panama Canal Authority capped transits at an average of 32 ocean-going vessels per day (10 Neopanamax, 22 Panamax) effective 30 July 2023, against a maximum sustainable capacity of roughly 38-40 per day.^[2]
• •Maximum draft for container vessels was cut from the normal 50 feet to 44 feet during the restrictions.^[1]
• •Daily transits were cut from the normal 38 down to 24 per day by November 2023, and on 1 January 2024 Gatún Lake stood almost 6 feet lower than a year earlier — the lowest January level on record.^[3]
• •Booking slots bottomed out at 22 per day (6 Neopanamax, 16 Panamax) in December 2023; announced further cuts to 20 slots in January and 18 in February 2024 were cancelled after November rains, and capacity was raised to 24 slots (7 Neopanamax, 17 Panamax) effective 16 January 2024.^[4]
• •In August 2023 more than 160 vessels were waiting to transit the canal, and Neopanamax-size ships faced waits of at least 17 days.^[8]
• •Only 15% of CHS grain shipments from the US Gulf to Asia moved via the canal in the fall 2023 shipping season, versus 85% a year earlier; rerouting around the Cape of Good Hope added about 30% more time and fuel, at roughly $30,000 per extra day at sea.^[5]
• •The Neopanamax draft limit returned to 50 feet on 16 August 2024, and for booking dates from 1 September 2024 total daily booking slots rose to 36 (10 Neopanamax, 20 Super, 6 Regular), in line with pre-drought transit levels.^[7]

Beginning on 19 November 2023 with the hijacking of the car carrier Galaxy Leader, Yemen's Houthi movement (Ansar Allah) attacked commercial shipping in the Red Sea and Bab el-Mandeb strait with drones, missiles and boarding operations, framing the campaign as a response to the war in Gaza. Most major carriers diverted around the Cape of Good Hope, collapsing traffic through the strait and the Suez Canal, while US- and UK-led coalitions mounted defensive escorts and strikes on Houthi positions. Attacks continued intermittently through 2025; the last reported strike on a merchant vessel, the Minervagracht, came on 29 September 2025, and on 11 November 2025 the Houthis announced a conditional suspension of maritime operations. Carriers began returning cautiously in early 2026, but transits remained far below pre-crisis levels.

Outcome: The Houthis announced a conditional suspension of attacks on 11 November 2025 (last strike 29 September 2025) following the Gaza ceasefire, and carriers began a cautious, still-incomplete return — Suez traffic remained roughly 60% below 2023 levels in early January 2026.

• •Ship transits through the Bab el-Mandeb Strait decreased by about 55% between 1 November 2023 and 28 February 2024.^[6]
• •Container vessel transits of the Suez Canal fell from 422 in November 2023 to 115 in November 2024, a 72% decline.^[5]
• •A June 2024 US Defense Intelligence Agency assessment found that alternate shipping routes around Africa add about 11,000 nautical miles, 1-2 weeks of transit time, and approximately $1 million in fuel costs to each voyage.^[7]
• •The IMF reported that trade volume through the Suez Canal dropped by roughly half year-on-year in early 2024 as ships diverted.^[2]
• •In the first week of 2026, Suez Canal traffic remained about 60% below the corresponding week of 2023, 100 days after the last Houthi attack.^[3]