one of the main paths across the US to the western part of the country, used by PIONEER s (= people who are the first to go and live in an unknown land) in the mid-19th century. The Trail crossed the GREAT PLAINS and the ROCKY MOUNTAINS before turning towards Idaho, Washington, and Oregon. The journey took around six months, and was extremely dangerous. The PIONEERs did not have good equipment, and they often suffered from illness or were attacked by NATIVE AMERICAN s .