The focus of this dissertation is to determine why states have chosen to cooperate with the federal government to enforce immigration laws. In order to identify why certain states are aligning with the federal government, an event history model is utilized to test state level factors leading to adoption of the 287g cooperative immigration enforcement program. The study concludes that the costs associated with sudden population growth increases the likelihood of state level immigration enforcement efforts, while, local level adoptions of the 287g program reduces the likelihood of statewide adoption.