Jersey City was a dock and manufacturing town for much of the 19th and 20th centuries. Much like New York City, Jersey City has always been a destination for new immigrants to the United States. In its heyday before World War II, German, Irish, and Italian immigrants found work at Colgate, Chloro or Dixon Ticonderoga. In 1908, the first permanent disinfection system for drinking water in the U.S. was installed on the water supply for the city by John L. Leal. The Hudson Tubes opened in 1911, allowing passengers to take the train to Manhattan as an alternative to the extensive ferry system. The Black Tom explosion occurred on July 30, 1916, as an act of sabotage on American ammunition supplies by German agents to prevent the materials from being used by the Allies in World War I.