LIBERAL, Kan. — The pro-immigration rally here two weeks ago was not the largest or most sophisticated, considering the tens of thousands of people who marched in places like Washington, Los Angeles and New York. It came together in just a few days, spread by word of mouth and a hastily written flier posted in stores. People picnicked or milled about as children played and vendors sold ice cream. They chanted "Sí, se puede" — yes, we can — but did not venture many more slogans than that. But the turnout of 800 or so in this windswept prairie town...