Trousdales - Early Illinois Residents

From "Early Land Grants of White County, Illinois 1814-54," by Harriet Vaught, an entry for my ancestor Alexander Trousdale (b. 1766), who purchased land in 1815 was found:

"Desc. Tax List of Lands Subject to Tax"
1815 June 6 - Date of Purchase
Patenter: Alexander Trousdale
Present _: Alexander & James Trousdale
NE 11 7 S 8 E (can be found on Illinois map here and here)
80 acres

Acquiring a Prairie Pioneer Certificate (Illinois) through my direct ancestor, Alexander Trousdale, may be put on my "to do" list. Other relatives have used another one of my direct ancestors, William Roark, who moved to Gallatin Co., Illinois in 1810, to obtain their certificate with a ribbon signifying the ancestors' residence in Illinois prior to statehood (3 December 1818). Perhaps starting with the Roark lineage might be smarter (and easier).