Which pope reigned longer than any other pope in history?

The pope who reigned longer than any other pope in history is Pope Pius IX. His papacy lasted from 1846 to 1878, a remarkable span of 31 years and 7 months. This extensive duration made him not only the longest-serving pope but also a significant figure in the history of the Catholic Church, as his tenure was marked by major events such as the First Vatican Council, which defined the doctrine of papal infallibility.

Pius IX's long reign also coincided with important political and social changes, including the unification of Italy, which greatly affected the papacy itself. His views and declarations had a lasting impact on the Church and its role in modernity, making his time as pope not only notable for its length but also for its historical significance.

Other popes, such as Pope John Paul II, had notably long reigns (over 26 years), but they did not surpass the length of Pope Pius IX’s papacy. This context solidifies why Pope Pius IX is recognized for holding the record for the longest reign in papal history.