The phenomenon of subfederal immigration regulation, in which state and local governments enact laws regulating immigrants within their jurisdictions, has become an enduring part of the American legal landscape. Though still the subject of occasional legal challenges, the focus of the national conversation has shifted from whether to have subfederal immigration regulation, to what form that regulation should take. States have taken widely varying approaches to immigration regulation; some like Arizona and Alabama have enacted restrictive, negative laws, while other states like Illinois and California have enacted laws to benefit the immigrants within their jurisdictions. Thus, in order to understand the immigrant experience in the United States, it is crucial to understand the climate created in individual states, by both state and local governments. Using seven years of empirical data (2005-2012), our study constructs an index to measure the immigration climate that sub-federal governments have created, on a state-by-state basis. By climate, we refer to the regulatory environment that immigrants experience in their everyday lives, as a result of the laws enacted by individual states to either benefit or restrict the immigrants within their jurisdiction. This Immigrants Climate Index (ICI) assigns a number, either positive or negative, to each immigration regulation enacted within a state; a states ICI score is the sum of those numbers. The purpose of the ICI is to express, in quantitative terms, the regulatory climate that immigrants face, allowing comparison among states and over a multiple year timeline.
