The work by Max Steinhardt and his co-authors Giovanni Facchini and Timothy Hatton on "Opening Heaven’s Door: Public Opinion and Congressional Votes on the 1965 Immigration Act" has now been published online at the Journal of Economic History.

Abstract:

The 1965 Immigration Act represented a radical shift in U.S. policy, which has been credited with dramatically expanding the volume and changing the composition of immigration. Its passing has often been described as the result of political machinations negotiated within Congress without regard to public opinion. We show that congressional voting was consistent with public opinion on abolishing the country-of-origin quotas but not with the desire to limit the volume of immigration. While the former initially reflected attitudes toward civil rights, the latter is consistent with contemporary expectations that the expansion in numbers would be modest.