I decided to explore a few of the transcribed schedules available online to see what causes were recorded.
In the 1850 mortality schedule for Potter County, Pennsylvania, we see the usual entries for dysentery, "tyfus" fever, croup, child birth, dropsy, consumption, various types of influenza, etc., but we also see some rather interesting causes of death. Nine month old Mary Ellis died from "eating caterpillars." Sarah A. Hitchcock died because she "choked on a bean." Two year old Mary Lawton "swallowed a brass button" and apparently was sick for 60 days from her accident before dying. There is also an unfortunate drowning of two year old Lorinda Nichols recorded.
Scarlet fever appears to have ravaged the population of Grayson County, Virginia according to its 1860 mortality schedule. We also see old age, croup, dropsey, pneumonia, influenza, and cancer among the causes of death. Ten year old Amanda W. Delp died from a fall.
The 1870 Jefferson County, Colorado schedule also gives us a few causes. We have a still born baby on the list and a few infants whose cause of death is listed as "debility." We have eye cancer, stomach and bowel influenza, lung fever, whooping cough, diphtheria, old age, and even a sore throat among the culprits. However, the most interesting entry is 3 month old Samuel Derby's "gravel."
Wright County, Iowa also has some interesting deaths. In their 1870 schedule, a 34 year old carriage maker by the name of Joseph Fulton was "killed in machinery." Nine year old George A. Peterson was "killed by eating ?" I'd love to know what that question mark was that he ate! Even if this transcription did not have a footnote describing the tragedy, one could look and see that the four deaths due to drowning in April 1870 must be from one incident. Dudley Gelman (age 65), William Rowen (age 30), Robert P. Rowley (age 35), and George Royce (age 28) apparently tried crossing the Iowa River when it was too high. Their 1880 census records Andrew Nelson's being crused in a sorghum mill and 10 year old Sherman Slaight's being "struck by Capston Sweep?" I don't know what a Capston Sweep is, but I don't think I'd like to be struck by one.
Roane County, Tennessee's 1880 schedule yields the murder of Dick Woods (age 38). Same Jones (age 35) was lynched. William Burnett (age 23) died of a pistol shot. Three year old William Sharp was burned. One year old Laura Renshaw died of worms and teething. That's the first time I've seen teething listed as a cause of death. John Keyhole (age 21) died from a kiln. John Eaton (age 12) was killed by cars on the railroad. James H. Day (age 30) "fell from trestel." One day old Bertheny Clark was "hurt by midwife." There is also a wide variety of disease listed among those enumerated.
Don't forget to check out the mortality schedules for the areas where your ancestors lived. They may add to your picture of what life was like for them in those days.