I'm betting some of those are "photographs which have been colored" rather than "color photographs". Back in the 19th and early 20th century there was quite an industry in adding the colors, altho' I've found a 1908 color photograph of Samuel Clemens. Check out "autochrome".

Come to think of it, I recently learned that John Logie Baird (Scots inventor) developed mechanical television, 3D television, full color television, even infra-red television, before 1930. Got me interested, so I built a replica. A whopping 32 scanning lines. How times have changed.

Tom
Edit: added "some" in first sentence.