This Ph.D. dissertation consists of three chapters on immigration economics. The main objective of the thesis is to explore how legal and unauthorized immigration systems interact and explore some of its consequences based on the case of the United States. Chapter 2 studies the U.S. immigration reform of 1986 and how it affected the migration dynamics of Mexican immigrants. Chapter 3 investigates the effect of documentation on immigrants' labor market outcomes. Chapter 4 studies the connection between a selective legal immigration system and the prevention of unauthorized immigration
