A swing state, sometimes called a battleground state, is one where both parties are considered likely to have a chance to carry that state in the Presidential election.
One way to understand the swing states is to see that they are the states that are most competitive because the vote there is likely to be close.
What actually determines who gets elected as President is not the nationwide popular vote, but who wins the Electoral College. Each state has a fixed number of electoral college votes, based largely on their population for a total of 538 electors. The president is chosen by a majority vote, and needs at least 270 electors to win.
Why a large majority isn't always the winner
This also explains why even a large majority of popular vote on the national level doesn’t guarantee election to office. To win, the candidate must also win in the states that will give them a majority of electoral votes, at least 270.
This is important in understanding swing states because the more electoral votes a state has, the more of interest it is for each of the two major candidates. So the battleground or swing states tend to be those with the largest number of electoral votes that also are considered winnable by either party. But the number of electoral votes is not the only criteria. For example, California which has 55 electoral votes, generally chooses a Democrat for President, thus is not considered a swing state - it’s not very competitive.
Swing states change over time
Over time the population of any state may increase or decrease enough to change the number of congressional representatives it has. The number of electoral votes each state has is equal to the number of Representatives it has plus two.
Obviously Presidential candidates structure their campaigns with the aim of winning at least 270 electoral votes and, as a result, the Presidency. If they are convinced that, say California will again vote for the Democratic Presidential candidate, the Republican candidate will focus on states he has a better chance to win. Many candidates will come to California to fund-raise, but that is a whole different issue.
Democracy Counts focuses on swing states
This is why Democracy Counts works to first hold audits in swing states. Election fraud is more likely to happen in swing states because that’s where fraudsters can have the biggest impact on the outcome. Changing a few thousand votes or even fewer in a swing state is easier than changing millions and, in some swing states can make all the difference in the outcome of the election nationwide. It has happened more than once. Of course, we’d love to audit every polling place and ideally that will happen someday. For 2020, however, we’ll be focusing on selected swing states.
What you can do
Determine if you are in a swing state or not. Ballotpedia offers good info about swing states for both the presidential election and for tight races for the senate. Contact us if you'd like to be involved in Democracy Counts citizen-run election audit.