The Role of Public Health Improvements in Health Advances: The 20th Century United States

David Cutler, Harvard University
Grant Miller, Harvard University

Mortality rates in the US fell more rapidly during the late 19th and early 20th Centuries than any other documented period in American history. This decline coincided with an epidemiological transition and the disappearance of a mortality "penalty" associated with living in urban areas. Little empirical evidence on what caused these improvements exists, however. This paper investigates the causal influence of clean water technologies--filtration and chlorination--on mortality in major cities during the early 20th Century. Plausibly exogenous variation in the timing and location of technology adoption is used to identify these effects, and the validity of this identifying assumption is examined in detail. Strikingly, we find that clean water was responsible for 44%, 74%, and 62% of the reductions in total, infant, and child mortality in major cities, respectively. Rough calculations suggest that the rate of return to these technologies was about 21:1 and that the cost per life year saved by clean water in 2003 dollars was about $500.