St. Charles (French: Saint-Charles; Spanish: "San Carlos") is a city in, and the county seat of, St. Charles County, Missouri. St. Charles the 2nd largest city in St. Charles County. It lies just to the northwest of St. Louis, Missouri on the Missouri River, and, for a time, played a significant role in the United States' westward expansion. It is the third oldest city west of the Mississippi, "The Little Hills", by Louis Blanchette, a French Canadian fur trader, and was the last "civilized" stop for the Lewis and Clark. The city served as the first Missouri capital. It is the site for the Saint Rose Philippine Duchesne shrine. It is also the home base for the St. Louis National Weather Service Forecast Office, serving central, east-central and northeastern Missouri.