This book is a compilation of CRS reports from 2017 and 2018 on Mexico, its background and US Relations. Congress has maintained significant interest in Mexico, an ally and top trade partner. The first chapter provides an overview of political and economic conditions in Mexico, followed by assessments of selected issues of congressional interest in Mexico: security and foreign aid, extraditions, human rights, trade, migration, energy, education, environment and water issues. The second chapter or report is a primer on US and Mexican water sharing. It focuses on the sharing of surface waters. The third chapter addresses seasonal agricultural import competition in the NAFTA renegotiation. Mexico’s production of some fruits and vegetables – tomatoes, peppers, cucumbers, berries and melons – has increased sharply in recent years, in large part to Mexico’s investment in large-scale greenhouse production facilities and other types of technological innovations. The next chapter provides an overview of the United States’ energy trade with Canada and Mexico. It quantifies current trends in US energy trade across the fuel categories, the potential for future trade, and key factors that may affect that potential – especially energy transportation infrastructure. The last report included in this book is a three-page report on Mexico’s transnational criminal organizations (TCOs), which have been identified for years as the greatest organized crime threat to the US given their strong links to drug trafficking, money laundering and other crimes.