Built during the California Gold Rush, Stockton's seaport serves as a gateway to the Central Valley and beyond. It provided easy access for trade and transportation to the southern gold mines. The University of the Pacific (UOP), chartered in 1851, is the oldest university in California, and has been located in Stockton since 1923. In 2012 Stockton filed for what was then the largest municipal bankruptcy in US history, which had multiple causes including financial mismanagement in the 1990s, generous fringe benefits to unionized city employees, and the 2008 financial crisis. Stockton successfully exited bankruptcy in February 2015.