The series counts crude and product tankers transiting the Strait of Hormuz each day, positioned from satellite AIS signals published by IMF PortWatch. Raw daily counts swing several-fold and are unreadable, so the chart plots the trailing 7-day mean. At its narrowest the strait is 21 miles wide, with shipping lanes two miles across — and Saudi Arabia, Iraq, Kuwait, the UAE and Qatar have no other sea route out of the Gulf.
The scale is why this count gets its own page: until its first-ever closure in March 2026 the strait carried roughly 20% of global petroleum liquids consumption — about 21 million barrels a day. The counts come from IMF PortWatch, which positions vessels daily from satellite AIS signals; this page reads the tanker count rather than the all-vessel total, because container traffic returning to the strait says nothing about crude. The page refreshes from the live data every hour and shows nothing cached, estimated or substituted.
The baseline is the strait's own pre-disruption traffic, so the reading answers one question: how much of normal is still getting through. A strait running at half its baseline is not a headline risk — it is a supply shock already in motion. Watch the level against the baseline, not the day-to-day wiggles.
The two directions mean opposite things for US equities. A fall against the baseline is the shock deepening: every missing tanker is crude that will not be delivered, which lifts the oil price, feeds inflation, tightens the rate path and reprices stocks. A rise back toward baseline is the genuine all-clear — traffic normalising before any headline declares the crisis over, with the pressure coming off the oil price and off equity valuations with it.
The history of oil shocks makes that chain concrete. In 1973 the embargo quadrupled oil in months, the S&P 500 lost 48% and inflation ran above 12%. In 1979 a supply cut of barely 5% doubled crude and forced the Fed to hike above 19%. In 2022 Brent briefly touched $139, CPI hit 9.1% and stocks fell 25%. None of those episodes closed Hormuz for a single day — the closure this page is counting is the first in the strait's history.
For US equities this count is the earliest link in the shock chain: every barrel that stops moving through Hormuz reappears in the Brent price, then in the CPI, then in the rate path, and finally in stock valuations. The transit count moves before the price does — which is why it gets its own page.