American voters go to the polls on Tuesday to elect a new president -- chief executive of the US government and commander-in-chief of the US military.
However, Americans do not vote directly for presidential candidates. Instead, after ballots are tallied in each state, state representatives, called electors, vote based on the state tallies in an Electoral College, a system which has been operating since 1788.
According to the system, a state's number of electoral votes equals the number of senators and House representatives combined from that state. As the number of House representatives are based on the size of population of each state, the number of electors varies from state to state.
California, the largest state, has 55 electoral votes, while the sparsely populated Alaska has only three. The District of Columbia, which has no representatives in Congress, has three electoral votes.
In all but two states -- Nebraska and Maine -- winner of the popular vote (the total number of votes cast by people in a given state) takes the state's total allotment of electoral votes.
In Nebraska and Maine, five out of the total nine votes are distributed based on voting in congressional districts, rather than in the state as a whole.
Under the Electoral College system, it is possible that a candidate who wins the popular vote may actually lose the election if he/she wins fewer electors' votes.
The Electoral College meet and officially vote for president and vice president on the first Monday following the second Wednesday in December in each presidential election year.
A majority of 270 electoral votes out of a total of 538 is needed for victory.
If no candidate receives a majority, the House of Representatives -- one of two houses of Congress -- must determine the winner from the three candidates who receive the most votes in the electoral college.
In 1824, John Quincy Adams did not win a majority in the vote and was elected president by the House of Representatives in this way.
The president and vice president take their oath and assume office on Jan. 20, following the election. Presidential election is held every four years and the president can be re-elected only once.
The Electoral College is established and runs on basis of the US political system, in which three separate branches -- executive, legislative and judicial -- check and balance each other under the Constitution, and also results from compromises and concessions of different interest groups.
In recent years, there have been calls for reform, but no material moves have been taken.
The following is a summary of electoral votes held by each state and the District of Columbia for the presidential election.
State
Electoral votes
Alabama
9
Alaska
3
Arizona
10
Arkansas
6
California
55
Colorado
9
Connecticut
7
Delaware
3
Dist. Of Columbia
3
Florida
27
Georgia
15
Hawaii
4
Idaho
4
Illinois
21
Indiana
11
Iowa
7
Kansas
6
Kentucky
8
Louisiana
9
Maine
4
Maryland
10
Massachusetts
12
Michigan
17
Minnesota
10
Mississippi
6
Missouri
11
Montana
3
Nebraska
5
Nevada
5
New Hampshire
4
New Jersey
15
New Mexico
5
New York
31
North Carolina
15
North Dakota
3
Ohio
20
Oklahoma
7
Oregon
7
Pennsylvania
21
Rhode Island
4
South Carolina
8
South Dakota
3
Tennessee
11
Texas
34
Utah
5
Vermont
3
Virginia
13
Washington
11
West Virginia
5
Wisconsin
10
Wyoming
3