I am doing a research project on the recent presidential general election and need to know which territories - if any - participate in it. From Wikipedia, I understand that Puerto Rico, American Samoa, and the U.S. Virgin Islands cannot vote in the election. Wikipedia did not state (as far as my research has so far taken me) if Guam is able to. Is Guam able to vote in the presidential general elections?
Only the states, and Washington D.C., can vote in the Presidential election.
The President of the United States is elected by the electoral college, which contains 538 members. The Constitution allocates electors to each state according to the number of Representatives each state has in the House of Representatives, plus the number of Senators that state has. It then allocates a number of electors to Washington D.C. no greater than the number of electors allocated to the least populous state.
Article II, §1 of the Constitution explains the way in which electors are allocated to the states:
Each state shall appoint, in such manner as the Legislature thereof may direct, a number of electors, equal to the whole number of Senators and Representatives to which the State may be entitled in the Congress
The Twenty-Third Amendment to the Constitution gives Washington D.C. a voice in the Presidential election as well:
A number of electors of President and Vice President equal to the whole number of Senators and Representatives in Congress to which the District would be entitled if it were a state, but in no event more than the least populous state
The Constitution at no point grants electors to United States territories, or any entity other than state or Washington D.C. Indeed, we can easily calculate that the number of electors in the electoral college is explained entirely by the aforementioned sections of the Constitution, leaving no room for representation of territories.
The Reapportionment Act of 1929 capped the number of Congressmen in the House of Representatives at 435. Each state is allocated two Senators, and there are 50 states. Adding the number of Congressmen and Senators together, we have 535 -- just three short of the number of electors in the electoral college.
These remaining three electors come from Washington D.C., which can have no more electors than the least populous state. Wyoming is currently the least populous state, possessing three electors (the minimum a state can have). Washington D.C. must therefore have three electors, and if we add that to 535, we have 538. Thus only electors from Washington D.C. and the states have a say in the Presidential election.