The contemporary anti-immigration movement in the United States is largely the product of decades of organizing, fundraising, and ideological work by one man — John Tanton, a Michigan ophthalmologist who founded, funded or otherwise nurtured more than a dozen nativist groups. The network of groups Tanton built up still dominates the politics of immigration in America, with one of those groups testifying to Congress at least 90 times, another at least 130 times, and a third playing a critical role in killing bipartisan immigration reform in 2007 and 2014. The network was also a key…