The Boxcar Children

US-only true first, and the census trap is confirmed: Rand McNally & Company (Chicago and New York), 1924, is the true first. Warner rewrote the book in 1942 for Scott, Foresman and Company, cutting it to roughly 15,000 words within a prescribed 600-word vocabulary for use as a school reader — that 1942 Scott, Foresman text is the version now universally known and is a "first thus," not the first edition. The University of Southern Mississippi de Grummond Collection's Warner finding aid confirms the Scott, Foresman attribution for the 1942 revision; note that Wikipedia attributes the 1942 revision to Albert Whitman & Company, which the archival source contradicts. Albert Whitman & Company published Warner's later series titles from 1949 onward and eventually became the exclusive publisher. No UK or foreign-language edition precedes 1924.