… is from page 13 of Chandran Kukathas’s superb 2021 book, Immigration and Freedom (footnotes deleted):
Yet it was not until the rise of Napoleon that any ruler took the trouble to locate a country’s borders with precision; not until the First World War that serious efforts were made to control the movement of people between countries; and not until the 1960s that the most prosperous countries in the world thought it necessary to distinguish legal from illegal migration.
DBx: Note that nations, including the United States, existed – and were conscious of, and confident in, their existence – before the occurrence of any of what Chandran here describes.