It’s time to go on the fall field trip. Usually, the teacher has already decided where the class is going. But this year, the teacher wants the class to decide by voting. Students will have to pick either the planetarium or the natural science museum. The teacher says, “All in favor of the planetarium, please raise your hands.” Then she does the same for the natural science museum. The planetarium wins by two in a 15-to-13 vote. This is an example of a popular vote – the most popular choice won.

Something like this makes the voting process seem simple. But when it comes to the highest-ranking vote in the United States, the process isn’t this straightforward. For example, consider the 2000 U.S. presidential election. Although Al Gore won the popular vote (more Americans voted for him), George W. Bush actually won the presidency. How did that happen? It’s because he was awarded the majority of the votes in the Electoral College.

Every four years, on the Tuesday following the first Monday of November, millions of U.S. citizens go to local voting booths to elect, among other officials, the next president and vice president of their country. Their votes will be recorded and counted, and winners will be declared. But the results of the popular vote are not guaranteed to stand because the Electoral College has not cast its vote.

VOTED LEAST POPULAR Four presidents have won an election with fewer popular votes but more electoral votes than their opponents had: John Quincy Adams in 1824, Rutherford B. Hayes in 1876, Benjamin Harrison in 1888 and George W. Bush in 2000.

The Electoral College, a system created by the framers of the U.S. Constitution, requires voters to vote for electors, who then cast their votes for candidates. Each state has a number of electors equal to the number of its U.S. senators (two in each state) plus the number of its U.S. representatives, which varies according to the state's population. More electors, means more votes. So, states with higher populations carry more voting power. Currently, the Electoral College includes 538 electors, 535 for the total number of congressional members, and three who represent Washington, D.C., as allowed by the 23rd Amendment. On the Monday following the second Wednesday in December, the electors of each state meet in their respective state capitals to officially cast their votes for president and vice president. These votes are then sealed and sent to the president of the Senate, who on January 6, opens and reads the votes in the presence of both houses of Congress. The winner is sworn into office at noon January 20. Most of the time, electors cast their votes for the candidate who has received the most votes in that particular state. However, there have been times when electors have voted contrary to the people's decision, which is entirely legal.

In cases where no candidate wins a majority of electoral votes, the decision is thrown to the House of Representatives by virtue of the 12th Amendment. The House then selects the president by majority vote with each state delegation receiving one vote to cast for the three candidates who received the most electoral votes. Two elections were decided by the House of Representatives: Thomas Jefferson in 1801 and John Quincy Adams in 1825.

WHO’S COUNTING? If you're wondering how someone becomes an elector, it turns out it's not the exact same process across the board. It can actually differ from state to state. In general, though, the two most common ways are: The elector is nominated by his or her state party committee (perhaps to reward many years of service to the party). The elector "campaigns" for a spot and the decision is made during a vote held at the state's party convention.