The number of U.S. citizens applying for passports has been rising over the last decade, but the proportion of people with the travel documents is still dwarfed by other countries.
Some 71 per cent of the population in the UK has a passport. But the U.S. is still way ahead of China, where only 1.5 per cent of the population can travel abroad.
Facebook, which was started by Mark Zuckerberg while he was a student at Harvard, has experienced phenomenal growth since it was launched in February 2004. There are now 750 million Facebook users worldwide, according to travel website Tripl, which compiled the figures.
Reasons given for the low proportion of Americans with passports include the costs of travelling abroad and the popularity of vacationing at home. Simon Winchester, who wrote 'The Best American Travel Writing', said that Americans to do have a history of international travel.
'There was essentially no empire and hence little by way of imperial legacy,' he said.
'The country is formidably isolated by thousands of miles of ocean from almost anywhere truly foreign, and getting abroad is very much more costly.
'Americans seldom went to seek their fortunes overseas, as British so often did . . . [and there] is little tradition of American exploration.'
Some 13.8 million Americans were issued with passports last year, which is significantly higher than ten years ago when 7.2 million were issued. It is a fall from 2007 though, when a peak of 18.6 million of the travel documents were issued.