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A libertarian think tank, reckon that eliminating all travel visas to the United States would add between $90 billion and $123 billion in annual tourist spending. By one estimate, introducing visa restrictions can lower trade and foreign direct investment between a pair of countries by as much as 25% .

Globalization has created a handful of metropolises that attract people, capital and ideas from all over the world, almost irrespective of how their national economy is doing. House prices in such places, unsurprisingly, outpace the national average. In our latest round-up of global housing, we find that prices have risen in 20 of the 26 countries we track over the past year, at an average pace of 5. 1% after adjusting for inflation. Prices in pre-eminent cities in these countries, however, have risen by 8. 3% on average.