Women officially were welcomed in 1972, wheelchairs three years later, and prize money was introduced in 1986, ushering in a professional era that rejuvenated the event and fortified its status as the world’s most prestigious road race. [...] nothing in more than a century has done more to shape how the Boston Marathon is perceived and how it will look in the future than the twin explosions at the finish line in 2013. [...] when the field of 30,000 leaves Hopkinton on Monday for the 119th race, the effect of those bombs will be seen not only in the ever-watchful security but in the way the runners and their supporters have responded to the unprecedented attack. “I don’t think it’s ever going to be just a race again,” said Desiree Linden, who returns this year in search of the American victory she missed by two seconds in 2011. [...] not until the bombings that killed three people and wounded 260 did the marathon became a touchstone for the resiliency of a city and its signature sporting event. Last year’s race became the centerpiece of the city’s recovery, and the calls to take back the finish line were answered when Meb Keflezighi became the first American man to win since 1983. A daughter of marathon runners, Flanagan grew up in suburban Marblehead with a reverence for the Boston race. On race day, already the state holiday of Patriots’ Day, the Red Sox will wear special uniforms with the city’s name on their chest.