I'm thumbing through my vintage copies and definitely don't see a lot of variety - most of the children are white and blonde, or at least brunette.
The African-American population of the US in the 1940s and 1950s was around 10% of the population, so you'd think an occasional character would show up.
Most Midwest households probably had never seen a Mexican person, but people in the South and Southwest definitely would have, so not sure why there aren't any Mexican children in the early books, too. Racism?
What are your thoughts?