Emotional day at the Boston Marathon

Ron McCracken of Dallas pays his respects at a makeshift memorial honoring to the victims of the 2013 Boston Marathon bombings ahead of Monday's 118th Boston Marathon, Sunday, April 20, 2014, in Boston. McCracken's race last year was cut short due to bombings and Monday's race will mark his 14th year running in the Boston Marathon. The memorial is where the second of two explosions happened last year near the finish line. (AP Photo/Matt Rourke)

2013 Boston Marathon survivors Celeste and Sydney Corcoran cross the finish line with Celeste's sister Acabbo, who ran the 118th Boston Marathon in Boston

2013 Boston Marathon survivors Sydney Corcoran and her mother Celeste are hugged by friends and family after crossing the finish line with Celeste's sister Acabbo, who ran the 118th Boston Marathon in Boston

A memorial to 2013 Boston Marathon bombing victim Martin Richard sits near the starting line of the 118th Boston Marathon Monday, April 21, 2014 in Boston. (AP Photo/Robert F. Bukaty)

Boston Marathon bombings survivors Adrianne Haslet-Davis, left, and Jeff Bauman greet near the finish line of the 118th Boston Marathon, Monday, April 21, 2014, in Boston. (AP Photo/Charles Krupa)

Race fans cheer runners as they start the 118th Boston Marathon Monday, April 21, 2014. in Hopkinton, Mass. (AP Photo/Michael Dwyer)

Boston Marathon bombing victim Crisci reacts after finishing the 118th running of the Boston Marathon with Reinertsen in Boston

2013 Boston Marathon survivors Corcoran and her daughter Sydney hug Acabbo, who ran the 118th Boston Marathon, after crossing the finish line in Boston

Race fans photograph and cheer for runners competing in the 118th Boston Marathon, Monday, April 21, 2014, in Boston. (AP Photo/Robert F. Bukaty)

Keflezighi of the U.S. reacts after winning the men's division of the 118th running of the Boston Marathon in Boston

A Boston Red Sox fan holds a sign supporting the Boston Marathon runners before a baseball game between the Red Sox and Baltimore Orioles at Fenway Park in Boston Monday, April 21, 2014. (AP Photo/Winslow Townson)

Running: Boston Marathon

Meb Keflezighi of the U.S. celebrates with his wifre Yordanos Asgedom after winning the men's division at the 118th running of the Boston Marathon

Wellesley College students cheer as runners compete in the 118th Boston Marathon Monday, April 21, 2014 in Wellesley, Mass. (AP Photo/Steven Senne)

Race fans alongside a "Boston Strong" slogan, watch the 118th Boston Marathon Monday, April 21, 2014 along the race course to Boston. (AP Photo/Steven Senne)

Photos of the day - April 21, 2014

Ernst Van Dyk, of South Africa, is presented the trophy after winning the men's wheelchair division of the 118th Boston Marathon Monday, April 21, 2014 in Boston. (AP Photo/Charles Krupa)

Marla Fogelman, right, hangs a banner on the second floor over Marathon Sports store, the site of the first bomb blast in 2013, before the start of the 118th Boston Marathon Monday, April 21, 2014 in Boston. (AP Photo/Charles Krupa)

A police officer walks past a Boston Strong banner as Wellesley College students affix the banner to the barricades before the start of the 118th Boston Marathon Monday, April 21, 2014 in Wellesley, Mass. (AP Photo/Mary Schwalm)

Athletes from the elite women field start during the 118th running of the Boston Marathon in Hopkinton

Mobility-impared runners David Abel, left, Juli Windsor, and Scott Rigsby compete in the 118th Boston Marathon Monday, April 21, 2014 in Hopkinton, Mass. (AP Photo/Michael Dwyer)

Kimberley Garcia of Boston poses with the slogan "Boston Strong" on her leg in Boston before boarding a bus to the starting line in Hopkinton, Mass., to compete in the 118th Boston Marathon Monday, April 21, 2014. (AP Photo/Matt Rourke)

A peace symbol bearing the words of 2013 Boston Marathon bombing victim Martin, "No more hurting people. Peace," is affixed to a pole near the finish line of the 118th Boston Marathon Monday, April 21, 2014 in Boston. (AP Photo/Charles Krupa)

Rob Ordman, of Calgary Alberta, wears the slogan "Boston Strong" on his head near the finish line before the start of 118th Boston Marathon Monday, April 21, 2014 in Boston. He's supporting his wife Beth, who is running in the race. (AP Photo/Charles Krupa)

Mike Poitras, of Dracut, Mass., wears the slogan "Boston Strong" on his head near the finish line before the start of 118th Boston Marathon Monday, April 21, 2014 in Boston. (AP Photo/Charles Krupa)

Mackenzie Petermeier, of Baxter, Iowa, who will be a guide for a blind runner, waits to board a bus in Boston to the starting line in Hopkinton, Mass., for the 118th Boston Marathon Monday, April 21, 2014. (AP Photo/Matt Rourke)

Anthony Bisenti cleans the finish line before the running of the 118th Boston Marathon Monday, April 21, 2014 in Boston. (AP Photo/Robert F. Bukaty)

A runner in the 118th Boston Marathon shakes the hand of a spectator holding American flags as runners' busses arrive near the start line Monday, April 21, 2014 in Hopkinton, Mass. (AP Photo/Stephan Savoia)

A woman pauses in front of a memorial for the victims of the 2013 Boston Marathon bombings at the site of the first bomb blast in Boston

A large crowd gathers to pose for photos at the Boston Marathon finish line, one day before the race, Sunday, April 20, 2014, in Boston. (AP Photo/Robert F. Bukaty)

After the bombings at last year's race, the 2014 event has become a symbol of the American spirit.