As the newest Cambodian city, Sihanoukville doesn't have a long history like Phnom Penh or Siem Reap. It was founded in 1960 after independence from France as a port, in order to communicate the city with international trade. The project was overseen by the government of Norodom Sihanouk.
The construction of the port began in 1955 and most of the families of the builders remained near the port, effectively becoming the first inhabitants.
During the Vietnam War, it became an intensive military port first in the service of National Front for the Liberation of South Vietnam and after 1970, with the regime of General Lon Nol, at the service of the United States.
With the success of the Khmer Rouge guerrillas in April 1975, the port was the last place to be evacuated by the US army. The SS Mayagüez was captured by militants of the new regime on 12 May. The US claimed that the ship was on international sea lanes, but the Khmer Rouge said that it was on Cambodian territory. It is known as the Mayagüez incident.
After the fall of the Khmer Rouge regime in 1979, the port of Sihanoukville recovered a great importance in the development of the country. With the opening of markets in 1999, the port became one of the main spots of economical growing of Cambodia.
In December 1999, Formosa Plastics bribed Cambodian officials and dumped 3000 tons of mercury laden waste into Sihanoukville, killing 3 people. Formosa Plastics also tried to dump the waste in the Nevada, USA
