When Missouri applied for statehood first in 1818 various proposals for boundaries were put forth including a western boundary at the mouth of the Nodaway River about west and the mouth of the Rock River (Illinois) opposite Rock Island, Illinois. Missouri was already going to be the largest state in area when it entered the Union and there was concern about making it even bigger. Sullivan was a delegate to the convention that was to ultimately declare the boundaries to be the two lines he had drawn.