The American Girl Doll History Mysteries

        The series comprises a total of 22 books by various authors and forms a companion series to the popular American Girl books; unlike Girl of the Year and other lines, they do not come with any doll or toy and acts as a stand-alone novel set in a particular period in American history. The characters were generally older, ranging from ages ten to fourteen, and the books were marketed as for ages ten and up. Many of the authors from this series later moved on to write for the Central Series. Several books from the series were later re-released in digital form by Open Road Integrated Media. (Wikipedia)

Titles in order of publication:

1. The Smuggler's Treasure by Sarah Masters Buckey (set in 1812 in New Orleans)
2. Hoofbeats of Danger by Holly Hughes (set in 1860, the Nebraska Territory)
3. The Night Flyers by Elizabeth McDavid Jones (in North Carolina in 1918)
4. Voices at Whisper Bend by Katherine Ayres (set in Pennsylvania in 1942)
5. Secrets on 26th Street by Elizabeth McDavid Jones (set in Chelsea in 1912)
6. Mystery of the Dark Tower by Evelyn Coleman (Harlem, 1928)
7. Trouble at Fort La Pointe by Kathleen Ernst (1732, Lake Superior)
8. Under Copp's Hill by Katherine Ayres (Boston, 1908)
9. Watcher in the Piney Woods by Elizabeth McDavid Jones (1865, Virginia)
10. Shadows in the Glasshouse by Megan McDonald (Jamestown in 1621)
11. The Minstrel's Melody by Eleanora E. Tate (set in 1904, in Calico Creek and St. Louis)
12. Riddle of the Prairie Bride by Kathryn Reiss (set in Kansas in 1878)
13. Enemy in the Fort by Sarah Masters Buckey (set during 1754)
14. Circle of Fire by Evelyn Coleman (1958, Middle Tennessee)
15. Mystery on Skull Island by Elizabeth McDavid Jones (1724, Charles Town, South Carolina)
16. Whistler in the Dark by Kathleen Ernst (1867 in Chicago and the Colorado Territory)
17. Mystery at Chilkoot Pass by Barbara Steiner (1897, Yukon Alaska)
18. The Strange Case of Baby H by Kathryn Reiss (San Francisco, 1906)
19. Danger at the Wild West Show by Alison Hart (1886, Louisville, KY)
20. Gangsters at the Grand Atlantic by Sarah Masters Buckey (1925, New Jersey)
21. Ghost Light on Graveyard Shoal by Elizabeth McDavid Jones (1895, Glenn Island, Virginia)
22. Betrayal at Cross Creek by Kathleen Ernst (1775-1776 in North Carolina)

American Girl Doll Mysteries by 

Danielle Smith and Daughter.