Mail-in ballots after Election Day? Supreme Court to decide.

The Supreme Court is reviewing a Mississippi case that could change when mail-in ballots must arrive to be counted nationwide.

The highest court in the nation is set to rule in a case that could lead to a major shift in how mail‑in voting works across the United States.

Mail‑in voting lets eligible American voters cast a ballot without showing up at a polling place on Election Day. Instead, they receive a ballot by mail, fill it out at home and send it back.That process is now under scrutiny by the U.S. Supreme Court, which is considering a case in Mississippi that could change when mailed ballots must arrive to be counted, not just in that state, but potentially nationwide.

More: Trump wants to eliminate mail-in voting. But 1 in 3 voters use it

Mail‑in voting allows eligible voters to cast a ballot without going to a polling place on Election Day. While rules vary by state, the basic steps are similar:

1. Check eligibilitySome states let any voter cast a mail ballot. Others, like Mississippi, limit mail‑in voting to certain groups, such as older adults, people with disabilities or voters who will be away from home.