Why do many historians use 1920 as the end of the Mexican Revolution?

Many historians use 1920 as the conventional end of the Mexican Revolution because it marks the conclusion of a decade of intense civil upheaval and the transition to a new political era.12

In 1920, the presidency of Venustiano Carranza collapsed following his attempt to impose a puppet successor, leading to his death while fleeing the capital. Subsequently, Álvaro Obregón was elected president, taking office on December 1, 1920. Obregón and his allies—a group known as the "northern dynasty"—sought to restore order and rehabilitate the country after years of savage conflict. His administration began the formal implementation of the Constitution of 1917, including land distribution and educational reforms, signaling a shift from open warfare to the institutionalization of revolutionary goals.314

While 1920 is a widely accepted convention, scholars acknowledge that the end point is debated. Some argue for the 1917 constitution, while others contend that revolutionary violence continued sporadically until the reforms were more fully realized under Lázaro Cárdenas in 1934 or even later.21