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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% .

Adolescents have always been keenly aware of how they are seen by their peers. But social media amplify this self-consciousness. Now that nearly three-quarters of American teens have access to a smartphone, many of them while away their days broadcasting then-thoughts, photos and lapses in judgment for immediate praise or scorn from hundreds of "friends".