Medicaid began as a poverty program for the poorest of the "worthy poor." In the next five decades, it extended its reach to cover a broad population for some of its services, including, for example, about half of all childbirths in the United States, and almost half of all long-term care services. The Affordable Care Act (ACA) pushed Medicaid's breadth further, although that extension was at least delayed in many states by the Supreme Court.
John V. Jacobi,
Multiple Medicaid Missions: Targeting, Universalism, or Both?,
Yale J. Health Pol'y L. & Ethics
Available at: https://digitalcommons.law.yale.edu/yjhple/vol15/iss1/7