History is Awesome!

Inspired by a friend's mention of "lynch mob" being anachronistic in The Mill (a BBC series set in a 1830s English textile mill), I went to Google Ngram and looked at the frequency history of "lynching", "lynched", "lynch mob", and "lynch mobs" in US English from 1800 to 2019 and the same graph for British English (loose text description of both follows).

Overall in US English, "lynching" and "lynched" are much more common than "lynch mob" or "lynch mobs", with the "lynching"/"lynched" ratio varying from 1 to 5 and (when "lynch mobs" appears at all) the "lynch mob"/"lynch mobs" ratio staying between about 2 and 3 throughout.
- There are some uses of all except "lynch mobs" from 1800 to 1805, tapering down to 0 almost linearly.
- From 1805 to 1829, all frequencies are 0 or very close to that.
- After 1829, "lynching" and "lynched" reappear.
- "lynching" is very close to "lynched" until 1869 when it passes it up, with both going up slowly until 1880.
- Starting in 1880, "lynching" and "lynched" start going up faster, peaking in 1902 and swinging up and down,with a peak in 1921 lower than 1902's and another in 1935 higher than both.
- "lynching" and "lynched" also peak in 1947 and 1968.
- Meanwhile, "lynch mob" and "lynch mobs" only start going up significantly in 1943 (when "lynching" and "lynched" are both at the bottom of a trough) and go up very slowly, with "lynch mob" at 2x to 3x the frequency of "lynch mobs" throughout that period.
- The use of all 4 goes up significantly from 1980 on.

The British English graphs are similar, except that:
- After tapering down to 0 in 1805 (as for US English), "lynching" and "lynched" don't reappear until 1835 (6 years later than in US English).
- The peaks for "lynching" after it passes up "lynched" in 1889 are more numerous and in different years (1893, 1904, 1919, 1934, 1946, 1959, and 1971), with 1946 being the most marked one.
- Only some "lynching" peaks (1893, 1932, 1946, and 1971) have matching "lynched" peaks (one of which, in 1932, is earlier than the corresponding one for "lynching" in 1934) and those are much less marked.
- There's no trough in 1943 for "lynching" and "lynched" when "lynch mob" and "lynch mobs" start going up.

Because the US English and British English have similarities but aren't identical, they can't reflect the same events through that period, but some events may cause similar features in both. I plan to start digging into historical timelines time and energy permitted, but any insight from others would be more than welcome.