Two-time Boston Marathon winner Joan Benoit Samuelson congratulates Edna Kiplagat on her victory in the 121st Boston Marathon.
Edna Kiplagat, left and Geoffrey Kirui, both of Kenya, hold a trophy together after their victories in the 121st Boston Marathon.
Geoffrey Kirui, of Kenya, wins the men's division of the 121st Boston Marathon.
Edna Kiplagat, of Kenya, wins the women's division of the 121st Boston Marathon.
Geoffrey Kirui, of Kenya, leads Galen Rupp.
Edna Kiplagat, of Kenya, poses for photographers after winning the women's division.
Spectators cheer runners.
Luke Puskedra, left, Meb Keflezighi and Jared Ward, all of the United States, run behind the leaders in Natick.
Leeland Cole-Chu identifies Ben Beach, center, as Beach begins running his 50th consecutive Boston Marathon
Edna Kiplagat, of Kenya, short hair at center, crosses the start line in the middle of the elite pack.
Spectators cheer runners at Wellesley College.
Emmanuel Mutai, of Kenya, leads the pack along the course of the 121st Boston Marathon.
Manuela Schar, of Switzerland, wins the women's wheelchair division.
Yemane Tsegay, of Ethiopia, fourth from left, leads the pack of elite men runners early in the race.
Marcel Hug, of Switzerland, wins the men's wheelchair division.
Tom Davis, of New York, wins the men's handcycle division.
Runners in the first wave cross the line at the start of the 2017 Boston Marathon in Hopkinton, Mass., Monday, April 17, 2017. (AP Photo/Mary Schwalm)
Marcel Hug, left, of Switzerland, moves ahead of Ernst Van Dyk, of South Africa, as they approach the finish line, to win the men's wheelchair division.
Meb Keflezighi, of San Diego, center, breaks from the start with Galen Rupp, as men's elite runners begin.
The elite female runners break from the starting line in the 2017 Boston Marathon.
The men's wheelchair division crosses the starting line.
Kathrine Switzer acknowledges the crowd as she is introduced before firing the gun to start the women's elite division.
Meb Keflezighi, of San Diego, sits at the start line as he ties his shoes before the beginning of the marathon.
Bobby Carpenter, gets a high-five from race director Dave McGillivray as he crosses the start line pushing Denna Laing. Carpenter was the first American-born player to be taken in the first round of an NHL Draft. Laing has been wheelchair-bound since being injured in the 2015 Women's Winter Classic.
A police officer and a working dog perform a security sweep at the starting line of the Boston Marathon.
Race participants pass through a security check in Boston to board buses for the starting line in Hopkinton.
Runners gather in Boston to board buses.