Why many island nations drive on the left

They mostly do so because of history and geography: British colonial rule exported left-hand traffic across a vast maritime empire, and islands—unconstrained by land borders—faced little pressure to harmonize with right-driving neighbors. Over time, vehicle imports and infrastructure locked the pattern in. Not every island drives on the left, but the ones that do usually trace it to colonial legacies or early rail and road decisions.

Historical roots: how left-hand traffic took hold

Keeping left has deep roots in Britain, with commonly cited origins in horseback and carriage practices that favored left-side passing for right-handed riders. The United Kingdom codified left-hand road travel in the Highway Act of 1835, decades before cars. Continental Europe, by contrast, shifted to right-hand traffic during and after the Napoleonic era, and later standardized it with the rise of motor vehicles. Those divergent paths set the stage for how driving norms spread globally.

How island nations ended up on the left

Colonial legacies carried across the seas

Britain’s maritime empire propagated left-hand traffic to ports and colonies from the Caribbean to the Indian and Pacific Oceans. In a few places beyond British control, early rail engineering and administrative decisions reinforced left-side norms that later migrated to roads.

Below are notable island nations (and archipelagos) that drive on the left today and the roots of that choice.

• United Kingdom and Ireland: The British system was formalized early; Ireland retained left-hand traffic after independence.
• Australia and New Zealand: Adopted British rules in the 19th century; uniform national road codes later entrenched them.
• Japan: Left-hand rail running began with British-built lines in the 1870s; left-side road traffic was standardized nationwide in the 1920s. Okinawa, shifted to right under U.S. rule after World War II, returned to left in 1978 (“730 Day”).
• Singapore, Sri Lanka, Malta, Cyprus, Mauritius, Seychelles, Fiji, Jamaica, Barbados, Bahamas, Trinidad and Tobago (and several other Caribbean islands): All inherited left-hand traffic under British administration and kept it.
• Indonesia and Timor-Leste: Left-hand traffic dates to the Dutch East Indies era, influenced by British practice during the early 19th-century interregnum and later codified; Timor-Leste continued left after independence.

Taken together, these cases show how British influence and early infrastructure decisions set a durable default that many islands chose to maintain after independence.

No land borders, less pressure to conform

Unlike continental states, islands do not have to align driving sides at border crossings, so they face fewer external incentives to switch. On land-connected continents, harmonizing with neighbors and trading partners helped right-hand traffic become dominant. For islands, maritime connections reduced that pressure, allowing left-hand systems to persist without cross-border friction.

Economics and practicalities that reinforce the pattern

Once a side is chosen, switching is expensive and disruptive: it touches road design, signage, intersections, driver training, vehicle fleets, and insurance. Island nations also rely heavily on imported vehicles, and supply lines from right-hand-drive markets (Japan, the UK, Australia) make left-hand traffic economical to maintain. Tourism further favors consistency: destinations prefer the driving side familiar to their biggest visitor groups.

These are the main factors that keep left-hand systems in place on islands.

• Vehicle supply: Affordable used cars from Japan and other RHD markets support left-hand traffic.
• Infrastructure lock-in: Roads, bus stops, and safety features (like pedestrian sightlines) are optimized for one side.
• Training and enforcement: Driver habits and licensing systems are built around existing norms.
• Tourism and trade patterns: Visitor flows and trade partners often share the same driving side, reducing incentives to change.

Together, these practical constraints make long-term continuity more rational than costly nationwide reversals—unless strong new economic incentives emerge.

Exceptions and switches: islands on the right, and why

Not all islands drive on the left. The Philippines, Cuba, Haiti and the Dominican Republic, Madagascar, Cape Verde, Taiwan, and Iceland drive on the right—typically reflecting Spanish, French, U.S., or mainland European influence, or later policy shifts to align with vehicle sources and regional norms.

Several island jurisdictions have changed sides, illustrating how economics and geopolitics can override history.

• Iceland: Switched from left to right in 1968 to align with mainland Europe and vehicle markets.
• Samoa: Switched from right to left in September 2009 so residents could import cheaper right-hand-drive vehicles from Australia, New Zealand, and Japan.
• Okinawa (Japan): Drove on the right under U.S. administration after World War II, then reverted to left in 1978 to match the rest of Japan.
• Taiwan: Drove on the left under Japanese rule; switched to the right in 1945 after the Republic of China took control.

These cases underscore that while history sets the baseline, practical economics and political transitions can determine the final choice.

The bottom line today

Roughly three-quarters of the world drives on the right, but a substantial minority—many in island states—remain on the left. For island nations, British colonial legacies, independence without land-border pressures, and enduring import patterns from right-hand-drive markets explain the persistence of left-side driving. Absent major shifts in trade or tourism, most are likely to stay the course.

Summary

Island nations often drive on the left because the British Empire exported that rule, islands lacked neighboring pressures to standardize with right-driving countries, and subsequent vehicle imports and infrastructure reinforced the choice. While notable exceptions and switches exist—driven by economics, politics, or alignment with key trading partners—the left-hand pattern on many islands is a historical inheritance sustained by practical realities.