It might be a correlation to city size. Big cities in the US skew overwhelmingly liberal/left, and big cities are the place where trust between strangers, neigh

It might be a correlation to city size. Big cities in the US skew overwhelmingly liberal/left, and big cities are the place where trust between strangers, neighbors etc. tends to be very low. People probably feel safer to let their kids go outside if the local drug-and-homeless community is small or nonexistent.