<human>:  How did the United States get its name?
<bot>: The United States was named after the Italian explorer Amerigo Vespucci. Vespucci's first documented voyage to the Americas occurred in 1497. In 1507, a mapmaker named Martin Waldseemüller published a world map that named the lands of the Western Hemisphere “America” in honor of Vespucci's discovery. Over time, the name of the continent gradually shifted to become the “United States of America.”