Apparently us Brits are not included in this. Just as well, otherwise I'd probably never get to visit DH's family again if they found my Mumsnet posts!!
14 Million Visitors to U.S. Face Social-Media Screening
Nearly all applicants for a visa to enter the United States — an estimated 14.7 million people a year — will be asked to submit their social-media user names for the past five years, under proposed rules that the State Department issued on Friday.
Last September, the Trump administration announced that applicants for immigrant visas would be asked for social-media data, a proposal that would affect about 710,000 people a year. The proposal would vastly expand that requirement to cover some 14 million people each year who apply for nonimmigrant visas.
The proposal covers 20 social media platforms. Most of them are based in the United States: Facebook, Flickr, Google+, Instagram, LinkedIn, Myspace, Pinterest, Reddit, Tumblr, Twitter, Vine and YouTube. But several are based overseas: the Chinese sites Douban, QQ, Sina Weibo, Tencent Weibo and Youku; the Russian social network VK; Twoo, which was created in Belgium; and Ask.fm, a question-and-answer platform based in Latvia.
www.nytimes.com/2018/03/30/world/americas/travelers-visa-social-media.html