 One or both of the brothers ran a trading post near where Big Bureau Creek empties into the Illinois River from 1776 until 1780 or 1790.The stream was called the "Chassagauch," "Chassagoach," or "Chachagouche" River on early maps of the region.These are European renderings of the Miami-Illinois language word "šaahšaakweehsiiwa," which once meant "copperhead" (agkistrodon contortrix) but now means "garter snake."