It no doubt aided the movement to deinstitutionalize patients with mental illness. Between 1955 and 1994, most state hospitals for the mentally ill were closed. This was done with the best of intentions, but the implementation led to the current mess where many severely mentally ill people are without adequate treatment and are homeless or imprisoned.
There's a great graph[1] showing per capita US institutionalization rates from 1934-2000, differentiating between prison, mental institutions and the combined total. The aggregate rate of US institutionalization is about the same as it was in 1954ish, the holding pen has just changed.
The graph is from a blog post on Volokh Conspiracy[2] about a paper from American Criminal Law Review [3] entitled "Is Mass Incarceration Inevitable"
