The Boston Marathon route, printed

Boston is run one way, from a small town west of the city to Boylston Street, and its hardest climbs wait until the legs have been worn down by miles of downhill.

The race starts in Hopkinton and heads east through Ashland, Framingham, Natick, Wellesley, Newton and Brookline before it reaches Boston itself. It loses most of its height in the first few miles, which drop steeply out of Hopkinton, and the runners who bank time there tend to pay for it later. After Framingham the road levels and rolls, and near halfway the students of Wellesley College line the course in what runners call the Scream Tunnel. Because the finish sits far below and well east of the start, Boston times do not count for world records, however fast the day.

The race is usually decided in Newton. A sharp descent into Newton Lower Falls past mile 15 is followed by a right turn at the fire station onto Commonwealth Avenue, and from there four hills come one after another. None of them is steep or long on paper. The last, Heartbreak Hill, rises past mile 20 towards Boston College, and its name goes back to 1936, when Johnny Kelley caught the leader, Ellison "Tarzan" Brown, on the climb and patted him on the back. Brown pulled away again and won. Boston College students crowd the top of the hill on race day.

From the crest it is mostly downhill through Brookline, with the Citgo sign above Kenmore Square in sight long before runners reach it, about a mile from the end. The last two turns are among the best known in the sport: right on Hereford Street, left on Boylston, and a long straight to the finish in front of the Boston Public Library. The race was first run in 1897, on Patriots' Day, and the April weather can go either way. In 2018 Des Linden became the first American woman to win since 1985, in cold rain and a headwind.