Washington - Americans took to Twitter in droves on Tuesday to post photos of themselves casting ballots in the long-awaited presidential election, sporting "I voted" stickers and urging others to do the same.Google also got in on the act, enabling users to click on the search engine's Doodle - made out of ballot papers with the second 'g' falling into a voting box sporting the US flag - to find their nearest polling station."Just cast my vote & my grandpa would be so proud!", @She_Weezy2012 tweeted, posting a picture of an "I Voted" sticker on her grey jumper, complete with the #ivoted hashtag, which was being used by hundreds of Twitter users."#iVoted for #TeamObama. Had to put an extra check for good measure!," @Stwo from New York said, adding a photo of his ballot paper which had the names of candidates in English and Chinese.QueuesMany complained of long waits at polling stations. "Whew 1 hour & 45 mins later," @trentfaris tweeted, but still proudly posted a photo of his "I voted" sticker.Others put up photos of them voting with their children - an initiative backed by First Lady Michelle Obama, who has encouraged Americans to take their kids to polling stations so they get an idea of the workings of democracy.Picswitch, a website that allows users to customise their Twitter profile pictures, had a large selection of logos provided by Barack Obama's campaign team that people were adding to their photos.The most popular was the generic "I voted" banner with Obama's campaign logo. But dozens of people had also chosen a shot of the US president taken from behind, with the caption "I've got his back."Online mapMany also checked in on the location-based social network Foursquare, to pinpoint exactly where they cast their ballot. By the end of the day, users will be able to see who voted across the United States on an online map."Happy Election Day" was trending nationwide on Twitter, as were the hashtags #TeamObama, #Obama2012, #rockthevote and #4moreyears. The social network also set up a dedicated page for the US vote.In Tampa, Florida - a key swing state - Republican was a top trending word, while in Richmond, Virginia - another crucial state in the election - #TeamObama trended.In the run-up to Tuesday's election, campaigns and other organisations have used social networks extensively to try and persuade people to vote and even beat the record 2008 turnout, when two-thirds of US voters cast a ballot.