Passports existed for centuries, but they were not used widely to control movement until the early 20th century.

Before the 19th century, travel documents were rare, informal, and selective, mainly letters of safe conduct for merchants or diplomats. Most ordinary people could cross borders without documentation.

During much of the 19th century, passport requirements actually declined, especially in Europe, as liberal ideas and new transport systems made travel easier and borders more open.

The decisive change came with World War I (1914–1918). Governments introduced mandatory passports to manage security, military conscription, and large population movements. Crucially, these wartime controls were not dismantled after the war.

In the 1920s, the League of Nations standardised passport formats and border controls, embedding them into international governance. By the mid-20th century, passports had become a universal and permanent tool for regulating international movement.