Running of the bulls into the turn at Estafeta ("la curva"), resulting in the installation of anti-slip surfacing, and now most of the bulls negotiate the turn onto Estafeta and are often ahead of the steers. This has resulted in a quicker run. Runners are not permitted in the first 50 meters of the encierro, which is an uphill grade where the bulls are much faster. Every year, between 50 and 100 people are injured during the run. Not all of the injuries require taking the patients to the hospital: in 2013, 50 people were taken by ambulance to Pamplona's hospital, with this number
Running of the bulls run for almost 700 years until it was abandoned in 1837. According to local tradition, the custom dated from the time of King John when William de Warenne, 5th Earl of Surrey, saw two bulls fighting in the meadow beneath. Some butchers came to part the combatants and one of the bulls ran into the town, causing a great uproar. The earl, mounting his horse, rode after the animal, and enjoyed the sport so much, that he gave the meadow in which the fight began, to the butchers of Stamford, on condition that they should provide a bull, to be