1800 - 1850
| 1842 | A few men came to the area now known as Dallas. Until then only Indians were along the banks of the LaCreole, where the game was plentiful. |
| 1843 | James A O’Neil was here and James W Nesmith, Jesse Applegate, Charles Applegate, Lindsey Applegate arrived. |
| 1844 | 45 families had started to arrive. Colonel Cornelius Gilliam headed a party that left Missouri and settled near Cynthian. James O’Neil built a grist mill on the Rickreall at Ellendale, west of Dallas. |
| 1845 | September 6, the first court case on record was held in Jefferson Institute; LC Lyle vs. John Stewart. First property tax was levied. 1/8th of one percent of the valuation of the property. |
| 1846 | April: the Jefferson Institute was built on the donated land claim of Carey Embree. The school was used as a church on Sundays. First circuit court: September 6, J.C. Lyle vs. John Stewart, held here as there was not courthouse. |
| 1850 | County seat was formed in Cynthian and the houses of Thomas Lovelady, Carey Embree, and John Lyle were used for holding court. January 8, O’Neil’s mill became the first post office. |