Last week, my vacationing family was stopped at not one, but two, internal checkpoints along Interstate 8 in Arizona and California and questioned about our citizenship. I couldn't help but think of a passage from the late historian Paul Fussell's Abroad: British Literary Travelling Between the Wars, describing the now almost unthinkable ease and anonymity with which people crossed national borders just a century ago: "[B]efore 1915 His Majesty's Government did not require a passport for departure, nor did any European state require one for admittance except the two notoriously backward and neurotic countries of Russia and the Ottoman Empire." How far we've come from effortless transit across borders to interrogations by armed, sweaty men along domestic highways.

With the exception of brief periods during the Civil War and the First World War, passports have only been required of Americans for (most) foreign travel since 1941. As recently as eight years ago, I drove to and from a house rental in Puerto Peñasco, Mexico, with no identification beyond my driver's license. Since 2009, though, a passport or similar document has been required to cross back into the United States from anywhere. After that second Border Patrol citizenship checkpoint in the desert, my wife suggested that we start carrying our seven-year-old son's passport domestically, in case we have to prove to some overbearing official that the kid is who we claim and has a right to be wherever he is. No law yet requires us to carry legal documents for Tony, but toting it seems a better idea than arguing with goons along a desert road.

Nominally an internationally recognized right, travel of all sorts has become creepingly bureaucratized in recent decades to an extent that has completely transformed the act of going from one place to another. Most of us adjust, treating the requirements as inevitable hassles — or even as the necessary security precautions that politicians and officials pretend they are. It's easy to forget how much has changed, until you're reminded of how much easier travel once was.

In the 1960s, "if you had a ticket, you could board a plane," and that ticket could be purchased with cash and little hassle (although at great expense, considering the regulated fares of the day). At the time, it wasn't unknown for a traveler to flag down a plane at the last moment to grab a seat, though that wasn't recommended procedure. When computer-industry millionaire and libertarian activist, John Gilmore, tried to board a flight in 2002 without showing identification, the result was a lost court case, and a TSA directive formalizing previously unofficial policy that travelers must present identity documents to fly.

"The biggest threat [to privacy] is public complacency," Gilmore told Reason's Brian Doherty. And it's true that identity checks at the border and TSA patdowns at the airport would be impossible if enough people refused to comply. Occasionally, people do push back. When the TSA started groping people and passing them through porn scanners, there was sufficient outrage to spark protests over Thanksgiving weekend in 2010. Three years later, the TSA has finally made the scanners a tad less revealing. But the machines are still in place, and they're still invasive. And you still have to show your papers.

In 1912, Fussell wrote, "D.H. Lawrence and Frieda Weekley … simply went, leaving from Charing Cross Station and crossing to Ostend and thence proceeding to Germany" by train without carrying documentation. In the 1990s, I used to volunteer "John Smith" when Amtrak clerks asked my name as I paid cash for a weirdly greasy seat on their always unreliable vehicles for the run between New York City and Baltimore. Good luck getting one of those tickets now, without a government ID. "Security measures" have been tightened in line with "federal Transportation Security Administration (TSA) guidelines." Why, yes they have — and that now includes random checks of carry-on luggage.

Even some private bus lines are getting nosy. Greyhound still leaves passengers relatively unhassled, but Peter Pan warns that "[v]alid photo ID confirming identity may be required during time of purchase and when boarding." Nevermind bus company policy, though. The TSA's VIPR teams are ready to check your ID and paw through your stuff at bus terminals, train stations and even truck stops, without warning. And they often bring friends from Customs, the Border Patrol and the local police.

Government officials have rationales for all of these intrusions, of course. Passports were first made mandatory during war years in fear of enemy spies (and fleeing conscription candidates). Airport security was tightened in response to hijackers. And then again after the terrorist attacks of 9/11 (even if most of the restrictions make no sense and provide no improvement to safety). And citizenship checks and other border restrictions are intended to deter illegal immigration (apparently by making the United States a much less attractive place to live). In the end, though, spies and hijackers and terrorists are just modern iterations of threats that have always existed. They provide handy excuses, however, for monitoring and controlling our movements for government officials who see such restrictions as ends in themselves.

Travel restrictions aren't quite unavoidable, so far. The checkpoints at which my family was stopped are confined to the area within 100 miles of the border. The TSA VIPR searches of bus and train passengers are still rare. Car and bus trips in much of the country still retain the potential for privacy and anonymity.

But that privacy and anonymity can no longer be assumed. Frankly, it's increasingly a crapshoot to head for any destination with an expectation that your documents will remain unperused and your possessions unpawed. In a few years, my kid may not be the only one carrying his passport to ease his travels within the country. I guess that puts us on roughly the same footing, a century later, as the "notoriously backward and neurotic countries of Russia and the Ottoman Empire."