The State of Penang in Malaysia, home to the country's second largest city as well as part of Malaysia's second most populous conurbation, has a relatively well-developed transport infrastructure. The city-state is well-connected by land, air and sea; the Penang International Airport is one of Malaysia's busiest, while the Port of Penang is the main harbour and transshipment hub within northern Malaysia. The North–South Expressway, the main highway along western Peninsular Malaysia, runs through Penang, while the two geographically separate halves of the state are now linked by two bridges and a ferry service.