Union City is a city in Alameda County, California, United States. As of the 2010 the current population is 74,800 and by 2030 the city will have 92,600 residents passing both *Alameda and *San Leandro which currently are larger. Union City was incorporated in 1959, bringing together the communities of Alvarado, Decoto, and New Haven. Alvarado was the original county seat of Alameda County in 1853, and the site of the first county courthouse is a California Historical Landmark (#503). Union City celebrated its 50th anniversary in 2009 with a year of community events. The San Francisco Bay Area Flight 93 Memorial is in Sugar Mill Landing Park. It was the first monument completed in the United States which was designed specifically to honor the passengers and crew of United Airlines Flight 93, which was bound for San Francisco, but was hijacked and crashed in rural Pennsylvania on September 11, 2001.