Ronald Wilson Reagan, who will be sworn in next Jan. 20 as the 40th president of the United States, is a native of rural Illinois who forged successful careers in rado broadcasting, the movies and politics.

Reagan, who will be two weeks short of his 70th birthday when he takes the oath of office, will be the oldest man ever assume the presidency -- a year older than William Henry Harrison was when he was inaugurated in 1841. The president-elect is the first professional actor to win the presidency and the first divorced person to attain that office.

The winner of yesterday's election was born Feb. 6, 1911, in a small apartment above the Pitney General Store in Tampico, Ill., where his father worked as a clerk. His father, Jack, a first-generation Irish-American, was a Roman Catholic, but his mother, Nelle, was a Presbyterian and Reagan has been a Presbyterian all his life. The family moved five times before Reagan's 9th birthday as his father searched for a job. Eventually, they settled in Dixon, Ill., where Reagan was graduated from Northside High School in 1928.

Reagan and his only brother, Niel, were graduated from Eureka College, a small christian school in Eureka, Ill. The future president majored in economics and sociology, but by the time he was graduated in 1932 his heart was set on a career in the new field of sports broadcasting. Within 18 months he landed a steady job at a Des Moines radio station, and soon the voice of announcer "Dutch Reagan" was familiar all over the midwest. s

During a trip to Los Angeles in 1937, Reagan was discovered by a talent scout for Warner brothers studio, which needed an All-American type to complete with MGM's Jimmy Stewart. Over the next 27 years Reagan made 54 feature-length films, playing the friendly, square-shooter role in most of them. He enlisted in the Army in 1942 but never left Hollywood, spending the war years making training films.

One of Reagan's regular co-stars was Jane Wyman, and he married the starlet in a highly publicized Hollywood ceremony in 1940. The couple divorced in 1948, and Wyman gained custody of their two children, Maureen and Michael. Reagan remarried in 1952, to Nancy Davis, then a budding actress. They have had two children, Patricia and Ronald. The president-elect has one grandson, two-year-old Cameron Reagan.

Reagan was active in the Screen Actors Guild throughout his screen career, and served six times as president of the union. (He is the first former trade union president to win election to the White House.) He has always been interested in politics, but his political views changed drastically as he approached his 40th birthday. He had enthusiastically supported Franklin D. Roosevelt and other liberal Democrats in every election, but at the end of 1940s he gradually switched sides.

By the end of the 1950s, Reagan had become a prominent national spokesman for right-wing causes. He worked hard for Republican nominee Barry Goldwater in the 1964 presidential election, and his nationally televised address for Goldwater at the end of that race brought in more than $1 million for the GOP nominee and started a boomlet that eventually drew Reagan himself into electoral politics.

In his first race for offce, in 1966, Reagan won the governorship of California by a million-vote margin over a fairly popular incumbent Democrat. cHe was reelected in 1970 by an easy, but smaller, margin. He mounted a last-minute campaign for the GOP presidential nomination in 1968; four years later he tried again and came close to taking the nomination away from then-President Gerald R. Ford.

At six-foot-one and 185 pounds, Reagan still has the wavy chestnut hair, clear voice and square shoulders familiar to fans from his movie days. He has been near-sighted since childhood and wears contact lenses. He has a mild hearing loss. He drinks occasionally but does not smoke. The Reagans live on a 688-acre ranch, Rancho de Cielo, overlooking the Pacific near Santa Barbara, Calif.

Vice President-elect George Herbert Walker Bush is a 56-year-old graduate of Phillips Andover Academy and Yale. He was awarded a Distinguished Flying Cross as a Navy pilot in World War II. He left his native New England in his early 20s, after college, to enter the oil business in Texas. His three drilling companies made him a millionaire.

Bush served two terms in the House and ran unsuccessfully for the Senate in 1970. He was Republican national chairman at the height of the Watergate scandal and also served as U.S. ambassador to the United Nations and to China and as director of the Central Intelligence Agency.

Bush and his wife, Barbara, have five children and two grandchildren. They are Episcopalian. They live in a large home in an upper-income suburb of Houston.