At 12:01 Thursday morning, the King County administration building here opened its doors to hundreds of couples waiting to apply for marriage licenses, the first day that same-sex couples were able to apply after Washington voters last month approved a ballot measure making it all perfectly legal. By 5 p.m. Thursday, the office had issued 481 licenses — most of them to same-sex couples — doubling the previous record for licenses issued in a single day, Barnaby Dow, a county spokesman said. Also around midnight, in another part of town, a different kind of party was taking place under the city’s Space Needle, where dozens of people had gathered to celebrate the vote to legalize recreational use of marijuana in the state. Besides approving same-sex marriage, Washington voters last month also passed ballot measure I-502, legalizing possession of up to an ounce of marijuana for those 21 and older. And even though smoking marijuana in public is still illegal under the new rules, and all marijuana smoking and possession remains illegal under federal law, the city’s police department has been told to stand down for now.