On its face, the legal showdown between Georgia Gov. Brian Kemp and Atlanta Mayor Keisha Lance Bottoms over the legality of the city’s face mask mandate is a dispute over the right balance between personal freedom and public health.

But the increasingly bitter feud between the Republican governor, an acolyte of President Donald Trump, and the Democratic mayor, a possible vice presidential pick who, herself, has tested positive for Covid-19, is also a microcosm of the fault lines — political, racial, geographic — hampering the country’s response to…