It is true your one vote will not make a difference in who gets elected. But your vote does count. While the popular vote does not determine who will be President, it can still have an effect. Will the President have a mandate or not? Have third parties garnered enough votes that the main parties may adjust their actions in order to win some of them back? The popular vote is important, and that is made up of all of our individual votes. I think it is particularly important to vote if you are voting for a third party, and it has nothing to do with whether or not your candidate will actually win.