Why do historians refer to the election of Thomas Jefferson as the Revolution of 1800?

Many historians refer to the election of Thomas Jefferson in 1800s as "The Revolution of 1800" because it was the first time that power in America changed from one party to another.

This marked US politics as a two-party system, despite the fact that many of them believed that the appearance of parties could do more harm than good. Because of those critics, Jefferson promised to govern as the Founders intended.