Securing America's Future Act of 2018 This bill amends the Immigration and Nationality Act to revise immigrant visa allocation provisions, including family-related visas. A nonimmigrant classification for parents of adult U.S. citizens is created. The diversity visa program is eliminated. Annual immigration levels are revised. The limit on the worldwide level of employment-based immigrants is increased. The H-2C visa temporary agricultural worker program is revised. A trust fund is established to provide incentives for such workers to return to their country of origin. DNA testing to establish family relationships is authorized. Employment eligibility verification provisions are revised. The Department of Homeland Security (DHS) shall establish an employment verification system. No federal, state, or local government entity or individual may prohibit or restrict a federal, state, or local government entity or official from complying with the immigration laws or assisting related federal law enforcement activities. The bill revises provisions regarding: (1) detention of aliens in removal proceedings; (2) illegal entry and reentry; (3) inadmissibility and deportability of criminal aliens, gang members, drunk drivers, and sex offenders; (4) repatriation; (5) asylum and asylum fraud; (6) unaccompanied alien children; (7) foreign students; and (8) visa fraud. The bill: (1) transfers authority for strengthening the southern border from the Department of Justice to DHS; (2) revises border security provisions; (3) provides for additional border security personnel; (4) authorizes new ports of entry along the northern border and southern borders; (5) authorizes National Guard border security activities; (6) provides contingent nonimmigrant status for certain aliens who entered the United States as minors; (7) authorizes appropriations for specified border barriers and infrastructure; and (8) establishes Operation Stonegarden to make border security grants to law enforcement agencies. DHS shall: (1) submit a southern border threat analysis, (2) establish the Integrated Border Enforcement Team program, (3) implement the Border Security Deployment Program, (4) review social media activities of visa applicants, and (5) establish a biometric exit data system.