In 1913 US life expectancy was 53 years. A few years later, in 1918 it would drop to 40 because of a flu pandemic that nowadays would almost certainly be preventable. In 1910, 8% of Americans could not read or write. In the south, that was 20%, which included 70% of southern blacks. Now, all those numbers are under 1 percent.
Leading causes of death were pneumonia, tuberculosis and diarrhea, all generally preventable or curable now. Nobody knew that smoking was dangerous. Cancer, even tumors considered trivial today, was a death sentence. Even appendicitis was a significant cause of death, especially in rural areas.