Black communities experience more extreme heat events in cities due to redlining--systemic denial of services --in Portland and elsewhere in the US. The visual is from The Gristlist of resources for understanding the effect of redlining on how Black communities experience heat.
Construction of freeways, including much of state-sanctioned public infrastructure in South California, is rooted in racism. Freeways destroyed unsegregated and Black neighborhoods just so white and affluent people could commute between city centers and burgeoning suburbs of Los Angeles and Portland, for example.