In the United States, there are two major political parties: the Democratic Party and the Republican Party. For much of the
19th century and the
20th century, most Granite Staters supported the Republican Party. They almost always voted for a Republican as president, for governor, and for representatives in the U.S. Congress and in the state government. The official color of the Republican Party is red, so for a long time New Hampshire was known politically as a red state.
Beginning in the late 1990s, though, many Granite Staters started supporting the Democratic Party and voting for Democratic candidates. The official color of the Democratic Party is blue, so when a majority of voters supported Democratic candidates, New Hampshire would be known politically as a blue state.
But because recent voters have changed their minds from one election to another about which political party to support, New Hampshire is now known as a
swing state. In one election it could swing to one party, and in the next election it could swing to the other party. The state swings so much politically that now it is known as a purple state, because purple is the color you get when you mix red and blue together.