Last updated: Oct. 25, 2026 · By Politics Elections Staff
U.S. elections are run by states and counties under a mix of federal law, state statutes and party rules. That is why registration deadlines, runoff rules and certification dates differ from one state to the next, and why election-night results are not final.
This page collects plain-English explainers from Politics Elections on how the system works: registering and staying on the voter rolls, counting and certifying ballots, choosing a president, and how Congress operates. Each explainer links its official sources and carries a “Data as of” date.
The explainers are general information, not legal advice; state and county election offices have the final word.
Voting and registration
Most states set a registration deadline before Election Day, but some let eligible residents register and vote at the same time. States also maintain voter rolls within limits set by federal law.
- How States Clean Voter Rolls Under Federal Law: what the National Voter Registration Act allows, when records can be canceled and the 90-day limit on systematic removals.
- Same-Day Voter Registration: The 24 States Allowing It: 24 states and Washington, D.C., offer some form of same-day registration; some allow it only during early voting.
Counting and certifying
A winner reported on election night is not the same as a certified winner. Counties finish counting, review provisional ballots and canvass results before states certify, and some races go to a runoff when no candidate meets the legal threshold.
- Runoff Elections: States, Rules and Election Dates: where majority thresholds trigger primary and general-election runoffs, and how Georgia and Louisiana set runoff dates.
- Election Results Certification: 2026 State Deadlines: there is no national certification day; state canvass and certification dates for eight states.
Presidential elections
Presidents are chosen through the Electoral College, not a single national popular vote. Nominees are picked through state primaries and caucuses scheduled under state law and each party’s rules.
- Electoral College: 270 Votes and the Popular Vote Compact: 538 electoral votes, 270 to win, Maine and Nebraska’s split rules, and why the popular vote compact is not in effect.
- 2028 Presidential Primary Calendar: Dates Set So Far: the Democratic National Committee’s six early 2028 contests, from South Carolina on Jan. 22 to Virginia on Feb. 29.
Congress
The election decides who serves in the next Congress, but the current Congress keeps working until its term ends. Senate rules and House district maps shape what each chamber looks like and what it can pass.
- Lame-Duck Congress: What Can Pass Before January 3?: the outgoing Congress keeps its full authority from Election Day until noon Jan. 3, 2027, including spending bills and nominations.
- Senate Filibuster: 60 Votes, Exceptions and Rule Changes: why ending debate on most bills usually takes 60 votes, while final passage and cloture on nominations need a majority.
- 2026 House Redistricting: States With New Maps: which states redrew congressional maps mid-decade, which maps apply on Nov. 3 and where courts or referendums stepped in.
Related guides
- 2026 Midterm Elections
- 2026 Senate Races
- Early Voting 2026
- How to Vote in Arizona
- How to Vote in Texas