The Nixon presidencies - one full term; one partial term - spanned a period of intense national distress for Americans. One win was by a tiny margin; the other by one of the largest in history. The divergence, in some measure, reflects the extremes in national temperament between 1968 and 1974, his years in office.
Nixon critics say his policies exacerbated the national anguish of the final years of the Vietnam war.
They charge that he staffed his administration poorly in many instances, allowed corrupt practices in high places, and championed attitudes that abused rather than united the nation. Finally, they say he miscarried the public trust in the presidency and, by his own deeds, ultimately obstructed justice.
On the other hand, he is cited for significant foreign policy initiatives with the Soviet Union and China, accomplishing the first arms control treaty with the former and opening diplomatic relations with the latter.
Although he started out advocating a free-market economy, he later imposed wage and price controls and ended the convertibility of the dollar into gold.
At one point, he attempted to outflank a Democratically controlled Congress by impounding money voted by the House and Senate when their legislation ran counter to his policy preferences. This failed.
Two of his Supreme Court nominees were rejected, but four others were confirmed by the Senate, including that of Chief Justice Warren E. Burger.
His vice-president pleaded no contest to federal income-tax evasion and resigned. Mr. Nixon himself, in the aftermath of the Watergate investigation, was the subject of impeachment proceedings in the House of Representatives. Eventually, he too resigned.
The pros and cons of the Nixon White House years are debated endlessly. Controversy surrounds many of the events cited in the following abbreviated chronology of that presidential period.
November: Richard M. Nixon defeats Democratic candidate Hubert H. Humphrey by 510,314 votes - a 0.3 percent margin.
Within a month of inauguration, takes eight-day tour of Europe; warms ties with French President de Gaulle.
May: Nominates Warren Burger of District of Columbia Court of Appeals to be chief justice of the Supreme Court. Confirmed by the Senate, 74 to 3.
June: Meets with South Vietnam President Nguyen Van Thieu, announces program to withdraw US troops from Vietnam. By mid-1972, troops would be down to 50,000 from peak of 500,000 in the mid-1960s.
July: Travels to Asia. Visits Romania - the first US president to visit there. Announces ''Asian Doctrine'': reduce US forces abroad; help smaller nations defend themselves by giving economic, military aid.
August: Declares a ''New Federalism, in which power, funds, and responsibility would flow from Washington to the states and to the people.'' Sends welfare proposal to Congress to put income floor under poor families at annual cost of $4 billion. Proposal defeated.
Oct. 15: Hundreds of thousands march in Washington against Vietnam war. Vice-President Agnew says it had been ''encouraged by an effete corps of impudent snobs who characterize themselves as intellectuals.''
November: Nominates Clement J. Haynsworth Jr. of South Carolina to Supreme Court. Defeated by Senate roll call, 55 to 45. Opponents question Haynsworth's alertness to the appearance of ethical impropriety.
December: Changes military draft to a lottery.
April: Senate refuses nomination of G. Harrold Carswell of Florida in a 51 -to-45 roll-call vote. Key senators object to Carswell's record on civil rights.
April 30: Announces US invasion of Cambodia, stating, ''We will not be humiliated. We will not be defeated.'' Protested by 1.5 million students on half the college campuses in US.
May: Four students killed, 10 wounded by national guardsmen during protest at Kent State University in Ohio. Two black youths killed, 10 wounded at Jackson State College in Mississippi.
June: Nominates Harry A. Blackmun for the Supreme Court. Senate confirms unanimously.
December: Announces use of deficit spending to stimulate economic growth.
January: Sends Congress record $299.2 billion budget with $11.6 billion deficit for fiscal 1972. ''By operating as if we were at full employment we will help to bring about that full employment,'' he says.
June: Ends 21-year trade embargo with Communist China.
July: Announces 1972 visit to Peking.
August: Secretary of State William Rogers says US will support the seating of Communist China at the UN.
August: Puts into effect new economic policy, with wage-price freeze. Suspends $35-an-ounce fixed gold price, a 40-year anchor on dollar's exchange rate.
October: Nominates Lewis F. Powell Jr., former American Bar Association president, to Supreme Court. Senate confirms, 89 to 1.
January: Nominates William H. Rehnquist, assistant attorney general, to the Supreme Court. Senate confirms, 68 to 26.
February: Visits People's Republic of China, promises cooperation. Agrees to subordinate Taiwan to mainland.
May: Becomes first US president to visit Moscow. Cold-war policy changes to detente. Signs Strategic Arms Limitations Talks treaty (SALT I). Reaches bilateral trade accord; plans joint scientific, space ventures; other pacts signed.
June: Burglary at Democratic National Committee headquarters at Watergate.
August: Republican National Convention nominates Nixon for a second term.
October: Ninety-second Congress enacts plan for general revenue sharing of $ 30 billion in federal revenues with state and local governments over a five-year period.
November: In presidential election, defeats Democratic candidate George McGovern by 18 million votes - a 23 percent margin.
January: Reaches agreement with North Vietnamese specifying cease-fire, withdrawal of US troops, return of prisoners of war.
April 1: Last known POWs released.
April 15: Act of Congress forces President to stop bombing Cambodia.
June: Nixon implicated Watergate conspiracy cover-up. Soviet leader Brezhnev arrives in Washington.
July: Reports reveal Nixon ordered secret bombing of Cambodia in early 1969, prior to ''official'' invasion in May 1970.
October: Arab-Israeli war. Secretary of State Henry A. Kissinger shuttles between Egypt, Syria, and Israel to end war and lay groundwork for continuing peace negotiations.
Vice-President Agnew pleads no contest to federal income-tax evasion and resigns. Rep. Gerald Ford of Michigan replaces him.
June: Precedent-setting trip to Israel, Syria, Jordan, Saudi Arabia; is the first president since FDR to visit Egypt. A week of talks in Moscow fails to produce nuclear arms limitations.
July: Proceedings begin to impeach Nixon.
August 9: He resigns. Vice-President Ford sworn in.
Sept. 8: President Ford grants Nixon ''full, free, and absolute pardon.''