Abstract Social welfare programs in the USA are designed to serve as safety nets for people in hard times, in contrast with the universal approach found in many other developed western nations. In a survey of cliometric studies of social welfare programs in the USA, we examine the variation in the safety net in the USA across states in the 20th century, the determinants of the variation and its impact on socioeconomic outcomes. The USA has always displayed substantial variation in the extent of the safety net because the features of most public social welfare programs have been and currently are determined by local and state governments, even after the federal government became involved in the 1930s. Differences across states persist strongly for typically a decade, although the persistence weakens with time, and there are some periods when federal intervention led to a re-ordering. The rankings of state benefits differ from program to program, and economic and political factors have different weights in determining benefit levels in panel data estimation of their effects. Variation in benefits across programs during the early 1900s had significant impact on labour markets, economic activity, family formation, death rates and crime.