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Boston Marathon Race Director Dave McGillivray, right, sends a group of Massachusetts National Guard members across the start line, launching the 129th edition of the race, in Hopkinton, Mass.

PHOTO: Jennifer McDermott

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The starting line in Hopkinton.

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Athletes gather in Hopkinton.

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State Police Trooper Cory Hetu takes a selfie with the group of race volunteers.

PHOTO: Jennifer McDermott

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Marcel Hug, the Silver Bullet, and other wheelchair racers at the start of the race.

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Four-time Boston Marathon winner Bill Rodgers and wheelchair athlete pioneer Bob Hall greet race volunteers at the start of the Boston Marathon.

PHOTO: Jennifer McDermott

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Colonial militia reenactors cross the finish line during a ceremony for the Patriot’s Day holiday prior to the Boston Marathon.

PHOTO: Charles Krupa

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An actor portraying Paul Revere tries to pull his horse, which refused to advance over the line, during a ceremony for the Patriot’s Day holiday at the finish prior to the Boston Marathon.

PHOTO: Charles Krupa

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The field of professional male runners.

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Field of professional female runners.

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A pack of runners crosses the starting line.

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Runners take off at the start of the marathon.

PHOTO: Boston Globe

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Marcel Hug wins his 8th Boston Marathon.

PHOTO: Charles Krupa

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Susannah Scaroni wins her second Boston Marathon.

PHOTO: Charles Krupa

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Marcel Hug, of Switzerland, right, and Susannah Scaroni, of the United States, hold up the winner’s trophy.

PHOTO: Charles Krupa

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John Korir, of Kenya, breaks the tape to win the men’s division.

PHOTO: Charles Krupa

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Korir celebrates with his brother after winning.

PHOTO: Maddie Meyer

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The women leaders run up Heartbreak Hill.

PHOTO: Boston Globe

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Kenya’s Sharon Lokedi set a course record with her time of 2:17:22.

PHOTO: Charles Krupa

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Des Linden announced her retirement before she ran the course for the last time.