https://www.newscientist.com/article/mg23030681-000-the-trut...

“The passport as an instrument of state regulation was born of the French revolution of 1789. At first, ordinary people were issued passes to control internal movement, especially to Paris. But after the king tried to escape, and foreign aristocrats attacked the revolution, the authorities started requiring such papers for exit and entry to the country. The revolution created one of the world’s first “nation-states”, defined by the “national” identity of its people rather than its monarchs’ claims.”

“But as the industrial revolution snowballed in the 19th century, there was pressure to allow free movement of all the factors of production – money, trade *and labour*. Passport requirements were widely relaxed across Europe — in 1872, the British foreign secretary, Earl Granville, even wrote: “all foreigners have the unrestricted right of entrance into and residence in this country”. The situation was similar in North America.”

https://fee.org/articles/passports-were-a-temporary-war-meas...

“In 1947, the first problem considered at an expert meeting preparing for the UN World Conference on Passports and Frontier Formalities was “the possibility of a return to the regime which existed before 1914 involving as a general rule the abolition of any requirement that travelers should carry passports.””