The Johor–Singapore Causeway is a 1.056-kilometre (0.66 mi) causeway consisting of a combined railway and motorway bridge that links the city of Johor Bahru in Malaysia across the Straits of Johor to the district and town of Woodlands in Singapore. It was the only land connection between the two from 1928 until 1998, when the Tuas Second Link opened.

The distance between Singapore's Woodlands Checkpoint and Malaysia's Bangunan Sultan Iskandar is approximately 2.4 km (1.5 mi). The causeway also serves as a water pipeline between the two countries.

It is one of the busiest border crossings in the world, with 350,000 travellers daily. Many Malaysians continue to live in Malaysia and commute daily (with either public or private motorised transportation) to Singapore, enduring extremely long journey times with extreme heavy traffic congestion on weekdays. The border is handled by immigration authorities of both countries at the Southern Integrated Gateway (Malaysia) and Woodlands Checkpoint (Singapore). Since 26 March 2022, both countries have permitted pedestrians to walk along the Causeway by foot, but this is not common; pedestrian walking is generally limited to instances of standstill vehicular congestion on the Causeway which prevents passengers from boarding regular-hour cross-border public buses after clearing immigration.