In early August, 1965, the Congress passed Medicare, and Johnson signed it into law. It was a much debated and fought battle, but he got it done. But even the most ardent supporters of Medicare was concerned that a sudden influx of patients would overwhelm the healthcare system at the time, so the new law had a built-in delay: it would go into effect in early August of 1966.
Hospitals across the nation got prepared for all these new patients. Many took out loans. They built new wings, or spent heavily to remodel old wings to bring them up to code. They hired and trained new doctors and nurses and radiologists and so forth, and bought ton of supplies. They prepared eagerly to collect these expected billions of federal dollars.
Then at the beginning of July, Johnson's assistant secretary of health announced that no Medicare dollars would go to any institution which did not comply with the Civil Rights Act of 1964. At that time there were over 1000 segregated or whites only hospitals. The day after Medicare went into effect, hospitals were 92% compliant with the Civil Rights Act; six months later it was 98%. It never was perfect, and segregation in hospitals didn't entirely end, but a huge gain was made it making healthcare in America more colorblind and equitable... and Johnson pulled it off with the carrot, instead of the stick. If he had announced the compliance requirement at the time the Medicare law was passed, many of these hospitals wouldn't have made the financial commitment. But come July of 1966, they were stuck.
Makes me smile every time I think about it.