I have lived in several Western American states, and now live in rural Kentucky. I think most of the Boer War figures would work for the period of about 1850 to about 2022 or later. The only limitation is the weapons. Some of the newer rifles and pistols would not work before the period of the Boer War but apart from that the clothing is still in use in some parts of the USA even today. Hats have mostly either gone out of style or changed to baseball caps and cowboy hats but a simple head swap would fix that problem.
I don't actually "do" the Boer War but have purchased all the figures (I think) and plan on buying a few more to use as American militia and civilians for several time periods. They would also work well for the Boxer Rebellion.
There are over 7 million horses in the United States today. About 2 million are kept as pets. The others are working horses in racing, ranching, farming, or transportation. I see people riding horses or riding in horse drawn wagons all the time around here.
I agree the Boers sets, especially the second of the two dismounted sets, are really useful and will serve in my VBCW forces. I'm also thinking they might be OK for Anglo-Irish War, Irish Civil War, 1920s and 1930s US industrial conflict and any civilian militia types from about 1900 upto the late 1930s. They work quite well with Redbox Boxer Rebellion civilians, gangsters and US cops and civilian sets. Not so much use for the mounted Boers in scenarios that interest me but I would still have liked to see some more pictures of these with some close ups of individuals. Good work.