1909 Boston Marathon

Although a record of 164 runners answered the starter’s gun, the biggest story was the heat, which saw the temperature climb to 97 degrees. The conditions were intolerable for 91 entrants, who exited early, and allowed the lead to change hands on nine occasions through 20 miles. New Hampshire mill hand Henri Renaud emerged from the fray to claim victory in 2:53:36. He passed through Framingham in 53rd place and, with two miles remaining, passed a weary Harry Jensen. Only Renaud was able to keep running without stopping over the final miles. 

(Source: Boston Marathon Official Guide)