Here's a look at what you need to know about the Boston Marathon, run from Hopkinton to Boston, Massachusetts. The finish line is in front of the Boston Public Library on Boylston Street.
April 20, 2015 - The 119th Boston Marathon is scheduled to run.
April 21, 2014 - The 118th Boston Marathon takes place. The winners are: Meb Keflezighi of the U.S. in the men's division and Rita Jeptoo of Kenya in the women's division.
The race's organizer is the Boston Athletic Association and its principal sponsor is John Hancock Financial Services.
Runners are categorized by gender, then by age. The age categories are: Men's and Women's Open (age 18-39), Masters (40-49), Veterans (50-59), Seniors (60-69), and 70 & Over. Qualifying times depend on the age of the participant on the day of the race.
Visually impaired participants are allowed, but must have a five hour qualifying time. There are also categories for wheelchairs and handcycles.
Runners come from all over the world to participate.
Participants must be 18 years of age on the day of the race and must meet certain time standards to qualify for their age group.
Best Men's Open time - 2:05:52 - Robert Kiprono Cheruiyot, Kenya - ( 2010)
Best Women's Open time - 2:18:57 - Rita Jeptoo, Kenya - (2014)
Best Men's Wheelchair time - Ernst Van Dyk (South Africa), 1:18:27 (2004)
Best Women's Wheelchair time - Wakako Tsuchida, Japan - 1:34:06 (2011)
Most marathons run - John A. Kelley finished 58 of the 61 races he ran.
April 19, 1897 - The first marathon is run and is 24.8 miles. The winner is John J. McDermott of New York, and his time is 2:55:10. There are 18 entrants, 15 starters, and 10 finishers.
1897-1968 - The race is run on April 19, Patriots' Day, a holiday commemorating the start of the Revolutionary War only recognized in Massachusetts and Maine. In those years that April 19 falls on a Sunday, the race is held the next day, Monday the 20th.
1918 - A military relay is held instead of the marathon due to the United States involvement in World War I.
April 19, 1924 - The race is lengthened to 26.2 miles to conform to Olympic standards.
April 17, 1967 - Kathrine Switzer becomes the first woman to receive a number to run in the Boston Marathon. She enters the race under the name K.V. Switzer and wears baggy clothes to disguise herself. Females are not officially allowed to enter until 1972.
1969 - Patriots' Day is changed to the third Monday in April, so the date of the race changes too.
1975 - A wheelchair division is added to the marathon. Bob Hall finishes the race in two hours and 58 minutes in a wheelchair.
April 15, 1996 - The 100th Boston Marathon is run. There are a record 35,868 finishers.