The US actually had quite a few cities with proportional voting in the early-mid 1900s. NYC for example had it from 1936 to 1947 when it was eliminated via referendum[1].
[1] https://www.fairvote.org/new_york_s_proportional_representat...
[1] https://www.fairvote.org/new_york_s_proportional_representat...
"[R]epeal advocates blamed proportional representation for the election of communists to the city council. While the communist issue might have doomed proportional representation, the true deathblow came when the Republicans joined the Democrats to oppose it. Republicans had been early champions of proportional representation, but defected due to their dwindling role within a diverse and mostly progressive minority coalition."