Some of the many ways Thomas Jefferson changed America include drafting the Declaration of Independence, writing several laws and purchasing the Louisiana Territory. These changes occurred over his very long political career.
Jefferson first rose to fame during the Revolutionary War as a member of the Second Continental Congress. There, he authored the Virginia Statute for Religious Freedom, generally seen as a model for the First Amendment. From there, he became the Governor of Virginia and held other positions in government before his election as President in 1800. In this role, Jefferson opposed a strong central government, preferring to leave power to the states.