Port Klang is a town and the main gateway by sea into Malaysia. Colonially known as Port Swettenham, it is also the location of the largest and busiest port in the country. As such, its economic progress has been greatly influenced by the port activities in its area. It is located about 6 kilometres (3.7 mi) southwest of the town of Klang, and 38 kilometres (24 mi) southwest of Kuala Lumpur.

Located in the District of Klang, it was the 13th busiest transshipment port (2004) and the 16th busiest container port (2007) in the world. It was also the 26th busiest port in by total cargo tonnage handled in 2005.

Klang was formerly the terminus of the government railway and the port of the State. In 1880, the state capital of Selangor was moved from Klang to the more strategically advantageous Kuala Lumpur. Rapid development at the new administrative centre in the late 1800s attracted businessmen and job seekers alike from Klang. At this time the only methods of transport between Klang and Kuala Lumpur were by horse or buffalo drawn wagons, or boat ride along the Klang River to Damansara. Due to this Frank Swettenham stated to Selangor's British Resident at the time, William Bloomfield Douglas, that the journey to Kuala Lumpur was "rather long and boring". He continued to suggest a train line be built as an alternative route.