Over the past several decades, Latinos have made up an increasing share of the U.S. population. States along the U.S.-Mexico border are at the forefront of this transformation and their policy responses have generated great debate over the issue of immigration and border security. Arizona's SB1070, signed in April 2010, is the latest effort to try to round up undocumented immigrants and stem their entry. What are some of the key demographic, political, and economic factors contributing to Arizona's growing immigrant population and shifting racial/ethnic composition?