The 20th century changed much of the American way of life, but the largest change came in Americans’ personal security, their and their families’ safety from life’s hazards. In 2017, Hurricane Harvey took 107 American lives and cost about $160 billion—and the federal government covered less than 10 percent of the losses. Epidemics like cholera and typhoid periodically ravaged 19th-century American towns and cities; by the early 20th century they were becoming rare. At a broader level, modern government by the late 20th century avoided or mitigated major shocks, notably of war at home and of major economic downturns. This greater insecurity coincides with growing irregularity and variability—what one researcher called rising “turbulence”—in Americans’ life course.