LOS ANGELES — Three days after being released from Martin Luther King Jr. Community Hospital, Gilbert Torres returned on a stretcher, a clear tube snaking from his nose to an oxygen tank. It was the last place he wanted to be.

But Mr. Torres, 30, who had just spent two weeks on a ventilator in the intensive care unit, wasn’t there because his condition had worsened. He was there to visit a new outpatient clinic for Covid-19 survivors, intended to address their lingering physical and psychic wounds — and to help keep them from needing to be readmitted.

WASHINGTON — America’s most celebrated infrastructure initiative, the interstate highway system, rammed an elevated freeway through the center of Claiborne Avenue in New Orleans in the late 1960s.