HILLSBOROUGH(sic), p-v, capital of Montgomery co. Ill, 64 s. Springfield, 768 W. It contains a court house, jail, 6 stores, 2 tanneries, 80 dwellings, and 400 inhabitants. (Haskell's Complete Descriptive and Statistical Gazetteer of the the United States...,1840)
HILLSBORO, A thriving village, capital of Montgomery county, on a fork of Shoal creek and on the line of the Terre Haute and Alton railroad, 64 miles south from Springfield. The growth of the place has not been rapid, but on the contrary, slow and steadily she has worked her way along to her present position. During the past year many improvements have been made, giving additional beauty to its whole appearance. Aaron H. Rountree, Postmaster. (Hawes' Illinois State Gazetteer...,1859)