The 2008 Puerto Rico Democratic presidential primary took place on June 1, 2008. It was an open primary. Puerto Rico initially planned to hold caucuses, as was done in 2000 and 2004, on June 7, 2008. In December 2007, an error in the plan was discovered; the caucus date should have read June 1, 2008. Puerto Rico also decided to conduct a primary, rather than caucuses. Puerto Rico sent 55 pledged delegates to the 2008 Democratic National Convention. These delegates were allotted on a proportional basis. The territory's delegation also included eight unpledged "superdelegates". Puerto Rico also selected one unpledged add-on delegate. Selection of the unpledged add-on delegate occurred at the Assembly of the Democratic Party of the Commonwealth of Puerto Rico on June 21, 2008 in San Juan. Polls were open from 8:00 am to 3:00 pm, prevailing local time, Atlantic Standard Time (AST) (UTC-4, same as Eastern Daylight Time). Hillary Clinton won the primary.