US presidential elections, since 2008. Dark blue: Democrats won the majority 4 times, light blue: they won 3 times, purple: Democrats and Republicans each won twice, light red: Republicans won 3 times, dark red: they won 4 times.
When elections are done in the United States, single US states are classified by their majority. In that context, in a blue state, the majority voted for a Democratic candidate, in a red state they voted for a Republican candidate. This classification has been in use since the year 2000. If people talk about a red or a blue state outside the context of an election, they refer to the party most people in the state usually support.
