Here's an article I can't read because it costs $22 and I prefer eating food instead. But this summary of the article says researchers have found racial disparity in whether or not you can expect help from a stranger if you have a medical emergency in public.
Some might point to this and say, "America's systemic racism is the reason a black guy having a heart attack will be left to die on the sidewalk by racist white Americans." But I don't see it that way. ("Of course you don't, Whitey!" - The Perpetually-Aggrieved Minority Reader.) Our public spaces are pretty segregated, so if blacks are being ignored in their health crises, they are probably being ignored by other blacks. Also, note that there's a socioeconomic component to stranger assistance, as well. Black communities are, on average, poorer than white communities, and it appears poor people are less-inclined to help others.
This is interesting because it goes against the hagiographic paeans we hear of disadvantaged neighborhoods. Far from the "we were poor but we were happy" stories that romanticize poor neighborhoods, the reality is that ghettos are more Hobbesian than Lockean.
This has implications for efforts to force integration. Reducing the average income of an area and increasing its diversity would create less-cohesive communities where people are less-inclined to help strangers. So have your unscheduled heart attack in a middle-income white town, not while visiting a big city.