Immigration is a national issue and a federal responsibility — so why are states so actively involved? Their legal authority over immigration is questionable. Their institutional capacity to regulate it is limited. Even the legal actions that states take sometimes seem pointless from a regulatory perspective. Why do they enact legislation that essentially copies existing federal law? Why do they pursue regulations that are likely to be enjoined or struck down by courts? Why do they give so little priority to the immigration laws that do survive? This Article sheds light on this seemingly irrational behavior. It argues that state laws are being pursued less for their regulatory impact, and more for their ability to shape federal immigration ...