Runners cross the Boston Marathon start line in Hopkinton, Mass., on April 18.
Approximately 500,000 spectators line the 26.2-mile course annually, making the Boston Marathon New England's most widely viewed sporting event,
Yemane Tsegay, left center, and Deribe Robi, right center, both of Ethiopia, lead the pack of runners just after the start in Hopkinton, Mass. Cool temperatures at the start warmed to 62 degrees by the time the winners reached the Back Bay. It was supposed to reach the mid-70s later in the afternoon -- an added challenge for the rest of the 30,000-runner field that left Hopkinton in four waves.
Boston police check bags of spectators near the finish line before the start of the 120th running of the Boston Marathon in Boston on April 18. Security was heightened after the 2013 Boston Marathon bombings.
Marcel Hug of Switzerland crosses the finish line to win the Men's Wheelchair division.
Fans cheer as runners pass Wellesley College in Wellesley, Mass.
Boston Marathon bombing survivor Adrianne Haslet, center, poses in Hopkinton, before running the marathon.
An image of MIT Police Officer Sean Collier adorns a tree near the finish line before the start of the marathon. Collier was gunned down during the frantic search for the suspects of the Boston Marathon bombings. His killing marked the start of a series of crimes the brothers allegedly committed in the manhunt's final 24 hours.
Tatyana McFadden of the U.S. poses for photographs with the family of Boston Marathon bombing victim Martin Richard after winning the women's wheelchair division.
Lemi Berhanu Hayle of Ethiopia runs the last yards to win the 120th Boston Marathon. Hayle won the men's race in 2 hours, 12 minutes, 45 seconds, pulling away from defending champion Lelisa Desisa as they crossed over the Massachusetts Turnpike heading into Kenmore Square.
Lemi Berhanu Hayle of Ethiopia crosses the finish line to win the 120th Boston Marathon. Hayle won by 47 seconds, with Yemane Adhane Tsegay another 30 seconds back to round out an all-Ethiopian men's top three.
Bobbi Gibb, the first woman to run the Boston Marathon in 1966, waves to the crowd at the finish line of the 120th Boston Marathon on April 18. Gibb ran 50 years ago when women weren't allowed to enter the marathon. Gibb, then 23, waited behind the bushes by the race start and snuck on in a hooded sweatshirt and Bermuda shorts. She finished in 3 hours, 21 minutes, 40 seconds.
Men's winner Lemi Berhanu Hayle of Ethiopia and women's winner Atsede Baysa of Ethiopia pose at the finish line after the 120th Boston Marathon in Boston on April 18.