The main purpose of this legislation is to protect the jobs of American railroad workers who are involved in cross-border freight traffic with Mexico. It aims to ensure that only qualified individuals operate trains that cross into the United States, thereby safeguarding employment opportunities for U.S. workers. Key provisions of the law include requirements for railroad carriers operating freight trains that cross the southern border into the U.S. These carriers must stop their trains at the border to conduct a crew interchange and any federally mandated safety testing.