Here's a story that suggests that the great state of Texas may be starting to catch up with the trend of state-level enforcement:

Lawmakers study immigration crackdown

By KELLEY SHANNON Associated Press Writer © 2008 The Associated Press April 21, 2008

AUSTIN – Conservative Texas legislators made it clear Monday they'll again push for strict state laws to crack down on illegal immigration when lawmakers convene in January.

A chief area they're likely to concentrate on is encouraging local police departments to work with U.S. officials to enforce federal immigration laws, which the House State Affairs Committee is studying.

"The fact of the matter is, our borders are broken," said Republican Rep. Debbie Riddle of Tomball, urging lawmakers in 2009 to battle illegal immigration. "My district, and I think the people of Texas, are demanding action."[More]

The reason this is important is that since there's little federal enforcement, and not much deportation, illegals are free to move about within the United States, just like the Okies were.

That means, as George Borjas noted, that if one state cracks down, the illegals move to the state next door.

A New Trend In Illegal ImmigrationThere's been a debate in labor economics about whether native workers respond to the negative wage impact of immigration by moving to areas that have fewer immigrants. Now we have another question to argue over: Do illegal immigrants move to states that are more willing to ignore their presence?

The reason this is important for Texas is that Arizona is cracking down, and Texas is practically next door to Arizona. (Physically, the state of New Mexico is in between, of course, but most illegals prefer Texas because it's more American.)