This page lists the winners of the Boston Marathon, which has been running continuously since 1897 and is the oldest annual marathon in the world. The first race, run in 1897, included only 15 runners, all of whom were men. Women were only officially allowed to run the race beginning in 1972, though female runners had unofficially participated beginning in 1966 despite the opposition of the Boston Athletic Association, the race sponsor. The Boston Marathon became the first major marathon to include a wheelchair division in 1975 for men, and added a wheelchair division for women in 1977.
Many marathon champions have repeated their feats in following years. The record for most repeated championships stands at 10, held by Ernst van Dyk in the Men's Wheelchair division. In the Men's Open division, Clarence DeMar holds the distinction of most wins with 7, and Catherine Ndereba tops the Women's Open division with 4. The United States has had more winners than any other country, followed by Kenya and Canada. The United States and Canada dominated the early years of the race, and it wasn't until the 36th race, in 1932, that someone from outside North America, Paul de Bruyn of Germany, won the race. During the period from World War II through the 1980s, there was much more national diversity among Boston Marathon champions, but the last two decades have seen Kenya emerge as the dominant nationality, especially in the Men's Open division, which (as of 2015) has been won by Kenyans in 19 of the past 25 years.
The 42.195 kilometres (26.219 mi) length of the marathon was not fixed before the 1924 Paris Olympics, and the Boston course varied as well. Prior to 1924 the course distance was approximately 24.5 miles (39.4 km). Even after the standardization of marathon lengths, the Boston course was off by nearly 200 yards from the correct distance until the mistake was discovered and corrected in 1927. The course grew gradually shorter in the 1950s as road re-construction straightened curves. This time, upon remeasurement the course was found to lack nearly 1200 yards, and was corrected beginning with the 1957 race. Due to these changes, the marathon recognizes several course records that are slower than previous records due to being run on longer courses. 26 world records have been set on the Boston Marathon course, one in the Men's Open Division, two in the Women's Open, 13 in the Men's Wheelchair, and 10 in the Women's Wheelchair.