“Europe has experienced a high level of immigration in recent years, driving debate about how countries should deal with immigrants when it comes to social services, security issues, deportation policies and integration efforts. Among these recently arrived immigrants are many who live in Europe without authorization. Coupled with unauthorized immigrants who were already in Europe, their numbers reach into the millions, though together they make up a small share of Europe’s total population. A new Pew Research Center analysis based on European data sources estimates that at least 3.9 million unauthorized immigrants – and possibly as many as 4.8 million – lived in Europe in 2017. The total is up from 2014, when 3.0 million to 3.7 million unauthorized migrants lived in Europe, but is little changed from a recent peak of 4.1 million to 5.3 million in 2016. Overall, unauthorized immigrants accounted for less than 1% of Europe’s total population of more than 500 million people living in the 28 European Union member states, including the United Kingdom, and four European Free Trade Association (EFTA) countries (Iceland, Liechtenstein, Norway and Switzerland). And among the roughly 24 million noncitizens of EU-EFTA countries living in Europe, fewer than one-fifth were unauthorized immigrants in 2017…”