How does the Electoral College work?

Every four years, 538 electors hailing from all 50 states plus Washington, DC cast their votes for president and vice president of the United States. A candidate needs a majority of 270 electoral votes to win each race. In this system, known as the Electoral College, each state gets the same number of electors as it has members of Congress — one for each member in the House of Representatives and one for each of the state’s two senators. This means that each state is guaranteed a minimum of three electors, regardless of population size. It also means that there is always a total of 538 electors, or equivalently, 538 electoral votes — that’s the sum of 435 voting members of the House, 100 senators, and three electors assigned to Washington, DC.

So, when voters cast ballots for president and vice president on Election Day, they’re actually voting for a slate of electors who have pledged to vote for their favored candidates. Most states (with the exceptions of Maine and Nebraska) use a “winner-take-all” system of choosing electors, meaning that — assuming electors vote according to their pledges — all of the state’s electoral votes are cast for the candidate that wins the majority of the state’s popular vote.

Electoral votes and population: Why one electoral vote accounts for 193,000 people in Wyoming and over 700,000 people in Texas or California.

Generally, states that are home to more people control more electoral votes. California — the largest state by population — has 55 electoral votes, while Wyoming — the smallest — has the minimum allocation of three. But because electoral votes are allocated according to seats in Congress, where each state holds two Senate seats regardless of population size, electoral representation varies quite a bit across states.

One way to think about electoral representation is to consider how many people each electoral vote represents, based on a state’s population. According to 2018 population estimates, one electoral vote in Wyoming accounts for around 193,000 people, while a vote in Texas or California accounts for over 700,000. For context, if all 538 electoral votes were distributed evenly among the US population, each vote would represent about 607,000 people.

Another way of thinking about electoral representation is to consider the difference between a state’s share of the nation’s total population and its share of all electoral votes. For example, Wyoming makes up about 0.18% of the US population but controls 0.56% of all electoral votes. This difference may seem minuscule, but it translates to approximately two additional electoral votes for Wyoming, relative to its population share. If Wyoming’s electoral share aligned with its share of the US population, it would have 0.18% of all 538 votes, which is about one electoral vote — but because votes are allocated based on seats in Congress, the state has the minimum of three votes in the Electoral College.

On the other end of the spectrum, California represents 12.1% of the US population and has 10.2% of all electoral votes. This means California controls roughly 10 fewer votes in the Electoral College than it would if votes were allocated based on population alone (because 12.1% of the total 538 votes is about 65 electoral votes, but California currently controls 55). For context, 10 votes is equivalent to the entire electoral share assigned to states like Maryland, Minnesota, and Missouri. It’s also the same as the combined vote shares of Iowa and Maine, or of all three states of Montana, Delaware, and Idaho.

Total population helps determine how electoral votes are allocated, but eligible voters determine how the votes are cast.

These examples demonstrate electoral representation based on each state’s share of the national population, and that’s because states receive representation in both the House of Representatives and the Electoral College according to the total resident population, not just according to how many voters live in the state. The resident population is all who live in the state at the time of the Census count, including both citizen and noncitizen residents, and both adults and children. Still, another way to view electoral representation is to see how the distribution of electoral votes compares to the distribution of eligible voters among states.

When determined according to the voting-eligible population nationwide, electoral representation looks a bit more equal across states. In particular, the two most populous states — California and Texas — are underrepresented by fewer votes when looking at representation among the voting-eligible population instead of the total resident population. These large states have higher proportions of non-citizen adults and a lower median age than many other states, so their shares of the voting-eligible population are smaller than their shares of the total US population. For example, California makes up 12.1% of the total US population but 11% of the citizen voting-age population; so by total population share, the state is about 10 votes underrepresented in the Electoral College, but by its share of eligible voters, the difference is closer to four votes.

What if electoral vote shares were equal to population shares in every state?

It’s important to note that even if electoral votes were allocated exactly according to each state’s share of the US population or share of eligible voters, the electoral process would not resemble a national popular vote. This is because of the winner-take-all rule for choosing state electors, currently used by 48 states and Washington, DC. According to this rule, all electoral votes go toward the candidate that earns the most votes in the state’s general election; therefore, votes cast for any other candidate do not earn any of the state’s electoral votes.

In other words, according to the winner-take-all policy, a candidate may earn 49.9% of a state’s popular vote and earn 0% of the state’s electoral votes. This explains how a candidate may win the national popular vote but, by failing to earn 270 electoral votes, may still lose the presidential election in the Electoral College — a scenario which has occurred in five US presidential elections, including the most recent election in 2016.

After this November's election, electoral votes will be reallocated based on Census results.

The total of 538 electoral votes is fixed, but how these votes are distributed between states can change as a result of the decennial Census. Every 10 years, the results of the Census determine how seats in the House of Representatives are apportioned, and states may gain or lose electoral votes accordingly. This November’s election will be the last of the decade before the reallocation of electoral votes.

Distribution of Electoral Votes
National Population Totals and Components of Change: 2010-2019
Citizen Voting Age Population 2014-2018