As long as I've been doing this job, there's been animation talent coming into Southern California from lands across the Atlantic and Pacific at a regular clip.
In the 1990s, most of the talent was in the hand-drawn area. Whole studios filled with artists from Ireland, Britain and northern Europe relocated to Los Angeles and Phoenix. Spielberg's Amblimation Studio (London) shut down and re-merged on the Universal lot as DreamWorks Animation. Bluth-Sullivan studios (Dublin) came to an end, but most of the staff quickly found its way to Fox Feature Animation in Arizona ...
The hand-drawn boom, of course, faded away near the turn of the century, but foreign-born animation talent has continued to flow to Southern California and other parts of the U.S. of A. I know this because the Animation Guild reviews O-1 immigration visas (documents for entertainment talent entering the country as leads with special abilities), and we've gotten a steady stream of O-1 visas over the past few years. Of late, the stream has grown to a small river, with one to three O-1s coming daily across my desk.
The people attached to these visas come to work in visual effects houses, game companies, and animation studios. They end up working at Pixar, DreamWorks, Disney, PDI, and any number of smaller, non-conglomerate facilities.
So what does it take for a foreign-born animator, designer, or compositor to qualify for the visa? He or she needs to be working as a lead. Her or she needs to have won awards or garnered articles in various publications. She or he needs to have letters of recommendation from peers in the field, credits on high-profile productions, and work experience with a credible studio. It's also important that the individual's salary be commensurate with her/his standing in the industry.
Now, applicants don't need to fulfill all of these requirements, but only half of them. But even then, candidates mostly get in. Over the years we have written negative letters on a number of O-1 applicants, but as far as we know, most of these folks ultimately end up working at the places who've applied to engage them *.
* This is the way the O-1 visa system has worked over the sixteen years we've been writing letters. Applicants generally have two bites at the apple, reworking their application or refiling if TAG generates a "thumbs down" letter. (Understand that most letters are positive -- when there's a problem, we contact the attorney preparing the documents and detail what our objections are. Sometimes applications are withdrawn, More often, they are reworked.)