When did passports and border crossing stations become the norm?
In general, letters of travel and passports existed from antiquity but were far from universal and werent required to cross borders. Details fluctuated over time, but its generally accepted that World War 1 was the genesis of the modern system. European governments introduced border controls for security and practicality reasons (controlling emigration of talented individuals during wartime). Following the war, the League of Nations held the 1920 Paris Conference on Passports & Customs Formalities and Through Tickets, which standardized the use of passports internationally for the first time. Whether they were required was still up to individual states, but the form and issuance of passports was standard. c. 1980 the UN added standards for scannable bar codes and the like. As far as the latter question goes, Americans didnt need passports to enter Canada in the year 2000. I grew up in Maine, and youd just show your drivers license as you drove over the border. It was only post-9/11 that things tightened up (especially in 2004), but a passport still isnt strictly required; there are other documents (NEXUS card, EDL, etc) that will work for land/sea crossings. Make sure you know the details, which are stricter for air travel than for surface travel.