Trolleybuses in Valparaíso, Chile, have provided a portion of the public transit service since 1952. The trolleybus system is the second-oldest in South America. The originally state-owned system has been privately owned since 1982, and since 1994 it has been Chile's only operational trolleybus system. Almost two-thirds of its vehicles were built in 1946–52 by the Pullman-Standard Company, and they are the oldest trolleybuses in regular service anywhere in the world. Those vehicles were collectively declared a national monument by the Chilean government in 2003. They helped the city gain its designation by UNESCO as a World Heritage Site, and have been called "a heritage sight in their own right" by at least one travel writer.