Thomas Jefferson (April 13, 1743 July 4, 1826) was an American statesman, diplomat, lawyer, architect, philosopher, and Founding Father who served as the 3rd president of the United States from 1801 to 1809. He was previously the second vice president of the United States under John Adams and the first United States secretary of state under George Washington. The principal author of the Declaration of Independence, Jefferson was a proponent of democracy, republicanism, and individual rights, motivating American colonists to break from the Kingdom of Great Britain and form a new nation; he produced formative documents and decisions at both the state and national levels.

During the American Revolution, Jefferson represented Virginia in the Continental Congress that adopted the Declaration of Independence. As a Virginia legislator, he drafted a state law for religious freedom. He served as the second Governor of Virginia from 1779 to 1781, during the Revolutionary War. In 1785, Jefferson was appointed the United States Minister to France, and subsequently, the nation's first secretary of state under President George Washington from 1790 to 1793. Jefferson and James Madison organized the Democratic-Republican Party to oppose the Federalist Party during the formation of the First Party System. With Madison, he anonymously wrote the provocative Kentucky and Virginia Resolutions in 1798 and 1799, which sought to strengthen states' rights by nullifying the federal Alien and Sedition Acts.

Jefferson and Federalist John Adams became friends as well as political rivals, serving in the Continental Congress and drafting the Declaration of Independence together. In the 1796 presidential election between the two, Jefferson came in second, which according to electoral procedure at the time, made him vice president to Adams. Jefferson challenged Adams again in 1800 and won the presidency. After his term in office, Jefferson eventually reconciled with Adams and they shared a correspondence that lasted fourteen years.

As president, Jefferson pursued the nation's shipping and trade interests against Barbary pirates and aggressive British trade policies. Starting in 1803, he promoted a western expansionist policy with the Louisiana Purchase which doubled the nation's claimed land area. To make room for settlement, Jefferson began the process of Indian tribal removal from the newly acquired territory. As a result of peace negotiations with France, his administration reduced military forces. He was re-elected in 1804, but his second term was beset with difficulties at home, including the trial of former vice president Aaron Burr. In 1807, American foreign trade was diminished when Jefferson implemented the Embargo Act in response to British threats to U.S. shipping. The same year, Jefferson signed the Act Prohibiting Importation of Slaves.

Jefferson, while primarily a plantation owner, lawyer, and politician, mastered many disciplines, ranging from surveying and mathematics to horticulture and mechanics. He was also an architect in the classical tradition. Jefferson's keen interest in religion and philosophy led to his presidency of the American Philosophical Society; he shunned organized religion but was influenced by Christianity, Epicureanism, and deism. Jefferson rejected fundamental Christianity, denying Christ's divinity. A philologist, Jefferson knew several languages. He was a prolific letter writer and corresponded with many prominent people, including Edward Carrington, John Taylor of Caroline and James Madison. Among his books is Notes on the State of Virginia (1785), considered perhaps the most important American book published before 1800. Jefferson championed the ideals, values, and teachings of the Enlightenment.

During his lifetime, Jefferson owned over 600 slaves, who were kept in his household and on his plantations. Since Jefferson's time, controversy has revolved around his relationship with Sally Hemings, a mixed-race enslaved woman, and his late wife's half-sister. According to DNA evidence from surviving descendants and oral history, Jefferson fathered at least six children with Hemings, including four that survived to adulthood. Evidence suggests that Jefferson started the relationship with Hemings when they were in Paris, some time after she arrived there at the age of 14 or 15, when Jefferson was 44. By the time she returned to the United States at 16 or 17, she was pregnant.After retiring from public office, Jefferson founded the University of Virginia. He and John Adams both died on July 4, 1826, the 50th anniversary of U.S. independence. Presidential scholars and historians generally praise Jefferson's public achievements, including his advocacy of religious freedom and tolerance in Virginia. Historians also admire President Jefferson's peaceful acquisition of the Louisiana Territory from France without war or controversy, in addition to the success of his ambitious Lewis and Clark Expedition. Though modern historians are critical of his involvement with slavery, Jefferson is overwhelmingly ranked as one of the greatest presidents in American history.

The United States Electoral College is the group of presidential electors required by the Constitution to form every four years for the sole purpose of electing the president and vice president. Each state appoints electors pursuant to the methods described by its legislature, equal in number to its congressional delegation (senators and representatives). Federal office holders cannot be electors. Of the current 538 electors, an absolute majority of 270 or more electoral votes is required to elect the president and vice president. If no candidate achieves an absolute majority there, a contingent election is held by the United States House of Representatives to elect the president, and by the United States Senate to elect the vice president.

Currently, the states and the District of Columbia hold a statewide or districtwide popular vote on Election Day in November to choose electors based upon how they have pledged to vote for president and vice president, with some state laws proscribing faithless electors. All states except for Maine and Nebraska use a party block voting, or general ticket method, to choose their electors, meaning all their electors go to one winning ticket. Maine and Nebraska choose one elector per congressional district and two electors for the ticket with the highest statewide vote. The electors meet and vote in December and the inauguration of the president and vice president takes place in January.

The appropriateness of the Electoral College system is a matter of ongoing debate. Supporters argue that it requires presidential candidates to have broad appeal across the country in order to win, while critics argue that it is not representative of the popular will of the nation when viewed without regard to the states.Its implementation by the states may leave it open to criticism; winner-take-all systems, especially in populous states, may not align with the principle of "one person, one vote". Almost 10% of presidential elections under the system have not elected the winners of the nationwide popular vote.Critics argue that the Electoral College system is less democratic than a direct popular vote and that the College violates the democratic principle of "one person, one vote."

Thus, a president may be elected who did not win the national popular vote, as occurred in 1824, 1876, 1888, 2000, and 2016. Critics object to the inequity that due to the distribution of electors, individual citizens in states with smaller populations have proportionately more voting power than those in larger states. This is because the number of electors each state appoints is equal to the size of its congressional delegation, each state is entitled to at least three regardless of population, and the apportionment of the statutorily fixed number of the rest is only roughly proportional. In addition, faithless electors may not vote in accord with their pledge. Further objection is that instead of spending equally on each voter in the nation, candidates focus their campaigns on just a few swing states. While polling data show having a direct popular vote for presidential elections is consistently favored by a majority of Americans, the popularity of the Electoral College has hovered between 35 and 44% in the 21st century.