To vote in US federal and state elections you must be: a US citizen, at least 18 years old on or before Election Day, a resident of the state where you register, and registered to vote by your state's deadline. Some states restore voting rights to felons after completing their sentence (varies by state). Non-citizens, including green card holders, cannot vote in federal elections. Some local jurisdictions allow non-citizens to vote in local elections only.

Voter ID requirements vary significantly by state. Strict photo ID states (like Georgia, Wisconsin) require a government-issued photo ID to vote. Non-strict states may accept alternatives like utility bills or bank statements. Some states (California, Illinois) require no ID for registered voters. If you don't have ID, many states offer free voter ID cards. Check your specific state's requirements at vote.gov before Election Day.

Gerrymandering is the manipulation of electoral district boundaries to favor one party. After each census, state legislatures redraw congressional and state legislative districts. By packing opponents into a few districts or spreading them thin, a party can win more seats than its vote share suggests. Example: Party A wins 55% of votes but 70% of seats due to favorable district drawing. Both parties have gerrymandered when in power. Some states use independent redistricting commissions to reduce this.

A primary election determines which candidate from each party advances to the general election. In closed primaries, only registered party members can vote. In open primaries, any registered voter can participate. In ranked-choice primaries, you rank candidates by preference. The general election is the final election where candidates from all parties compete for the actual office. Primaries often have much lower turnout — which means each vote has more impact.

Ballot measures (also called propositions, initiatives, or referendums) are direct votes on laws or constitutional amendments, not on people. Citizens or legislatures can put measures on the ballot. A simple majority (50%+1) usually passes a measure. Some constitutional amendments require a supermajority (60% or 2/3). Ballot measures cover things like tax increases, abortion rights, marijuana legalization, and minimum wage — often more impactful than individual candidate races.