The longest papal conclave in history lasted nearly three years, specifically 1,006 days, from 1268 to 1271. This conclave followed the death of Pope Clement IV and was marked by intense factional deadlock among the 17 cardinals, requiring extreme measures such as locking the cardinals in seclusion to reach a decision. It ended with the election of Pope Gregory X on September 1, 1271

. Other notably long conclaves include the 1740 conclave, which lasted about six months, and the longest conclave in the past 200 years, which lasted 51 days in 1831

. However, modern conclaves typically last only a few days.