The Development of Parties. Washington hoped that political parties could be avoided, but they began during his Presidency. Measures sponsored by Washington's own administrations, particularly those implementing the financial and tariff policies of Secretary of the Treasury Alexander Hamilton, caused sharp differences of opinion that led to the forming of two political parties. The Federalists supported Hamilton's views. The Republicans, led by Thomas Jefferson, opposed them. (The Republicans later formed the Democratic-Republican party, which developed into the present Democratic party.)

In general, Jefferson's followers were farmers, small shopkeepers, and tradesmen who felt that the Federalists favored government for and by the wealthier classes. The Republicans cited several actions of the Washington administration, in addition to the economic policies of Alexander Hamilton, to make a case that the Federalists were antidemocratic. They pointed, for example, to Washington's use of federal troops against the Pennsylvania farmers who participated in the Whiskey Rebellion of 1794 and to Washington's refusal to support revolutionary France in its war with Great Britain, which they viewed as siding with the monarchical British against the democratic French.

Republicans and Federalists also differed over interpretation of the Constitution. The Republicans, wishing to limit the authority of the federal government, advocated strict interpretation. The Federalists favored a broad interpretation to give the central government the most power possible. This issue, related to states' rights, has continued to be a matter of contention throughout the nation's history.

In the 1796 election, the Federalists retained the Presidency, under John Adams. However, Adams defeated Jefferson by only three electoral votes and his administration marked the beginning of the Federalist party's decline. Under Adams, the nation became involved in an undeclared war with France. During this conflict, the Federalists in 1798 pushed through Congress the restrictive Alien and Sedition Acts. These laws, which were used to curb dissent, gave the Republicans a further opportunity to brand the Federalists as antidemocratic.

In 1800 Jefferson was elected President. Unlike his two predecessors and their supporters, he believed that the judgment of the masses of the people could be trusted, and he sought to promote this democratic idea. Jefferson was reelected in 1804.

Lewis and Clark reached the Pacific Ocean in 1805.Lewis and Clark reached the Pacific Ocean in 1805. Lewis and Clark reached the Pacific in 1805 after crossing the Rockies and descending the Snake and Columbia rivers. Thomas Jefferson had commissioned them to explore the Louisiana Territory and the Oregon region.Westward Movement in America by 1790.Westward Movement in America by 1790. By 1790, the East Coast had been largely settled, and Americans had pushed beyond the Appalachians. Two new frontiers—the Northwest Territory and the Old Southwest—had opened.