Jonathan V. Last provides scads of helpful context to the 2012 version of the quadrennial GOP vein-throbber over illegal immigration. After providing some legal and legislative history, and making the point that Shikha Dalmia mentioned here about tuition coming largely from state sales taxes (which everyone pays regardless of documentation status), Last concludes:
To hear Mitt Romney tell it, you'd think the University of Texas at Austin was overrun with the children of illegals, taking slots and taxpayer money from smart kids in New Jersey who've dreamt about being Longhorns their whole lives—and would have gone to UT if only they could have afforded the out-of-state rate. But the reality is very different. It turns out that of the 1.8 million students enrolled in Texas higher-ed, only 16,476 students are illegals (the state refers to these kids as "affidavit students"). Of those, 12,028 go to two-year community colleges. For the most part these schools have noncompetitive admissions and hardly any out-of-state students. A vanishingly small number go to the state's competitive flagship schools: The University of Texas has 612 of them; A&M has 362. Romney's fretting about a "$100,000 discount" being given to illegal immigrants is something like an argument for abortion rights centered around rape and incest. [...]
The only definitive conclusions the Texas experiment offers are about Mitt Romney.