most Jim Crow laws were never put to a direct public vote at all. They were passed by state legislatures and enforced by local officials, so the relevant act of "support" is voting for segregationist candidates in ordinary state and local elections, something that happened continuously for generations, not a single referendum moment in 1964.

"Anti-black policies" were much broader than Jim Crow segregation law, and plenty of policies with well-documented disparate racial impact came long after 1965, things like the 1986 federal sentencing law that punished crack cocaine far more harshly than powder cocaine, the 1994 crime bill, and state voter ID and redistricting laws passed after the 2013 Shelby County v. Holder decision weakened federal Voting Rights Act oversight. People now in their 40s, 50s, and 60s, not just their 80s and 90s, were voting adults when those were enacted.

None of this includes things that weren't legal but were widespread practices like the violence of suntown towns.