Strengthening American Communities Act of 2018 America's College Promise Act of 2018 This bill amends the Higher Education Act of 1965 to require the Department of Education (ED) to establish programs that assist students in paying for the costs of higher education. Specifically, ED must establish grants to assist students in paying for the costs of attending community colleges, historically black colleges and universities, minority serving institutions of higher education (IHEs), or nonprofit IHEs. This bill appropriates funds for such grants. In addition, ED must establish grant programs to pay the costs of an undergraduate education for students who commit to working for at least three years in public service jobs upon graduation. Finally, ED must cancel a certain percentage of the amount a borrower owes, based on the number of years of public service employment, on federal student loans made after this bill's enactment.