Following on the post on Google Trends for the terms genealogy, ancestry, family tree and family history, here’s the same set from Google Ngram. It goes back to 1800. I choose the English (2019) database for comparison encompassing books published in both the UK and USA.
“Family Tree” gains in popularity throughout the period although lagging the others.
“Ancestry and “Family History” show a similar evolution.
“Genealogy” declines until 1950, it closely parallels “Family History” after 1900.
A friend suggested the increase from 1870 to 1900 was due to affluent families looking to establish a pedigree, leading to a spate of fraudulent genealogies?
The period from 1900 to 1970 was one of status quo or decline in popularity. Many attribute the subsequent increase to the effect of “Roots: The Saga of an American Family”published in 1976 and the 1977 TV mini-series.