The president of the United States in 1980 was Jimmy Carter until January 20, 1981. Ronald Reagan became the 40th president of the United States starting with his inauguration on January 20, 1981. Reagan served two terms from 1981 to 1989 after winning the 1980 presidential election against incumbent Jimmy Carter. So in the year 1980 itself, the president was Jimmy Carter until the inauguration of Ronald Reagan in early 1981.