I went through this phase in 4th and 5th grade. I haven't reread them since so cannot say how they translate to an older reader. I say go for it regardless.
The Orphan Train Quartet, Land of Hope trilogy, High Trail to Danger and sequels- all by Joan Lowery Nixon- this and Rinaldi describes 4th grade (which I would place as the minimum level for readers).
Hang a Thousand Trees with Ribbons and almost anything else by Ann Rinaldi (though this one is my absolute favorite)- again, 4th grade and the way I learned history. Depending upon age, some may need discussion.