What started in the 1820s as a fur trading post along the Missouri river?

Why put notes in wailing wall? What are the main uses of water from the Colorado River? Do all earths oceans connect to form a single world ocean? What is the sea east of the Antarctic Peninsula? What is the major river that flows through Kenya emptying into the Indian ocean? Where was Charles Wilden the man bowing his head and praying in Grace painting taken in the early 1900's from? What is a career barrier? Who the artist of nebamun hunting in the marshes? What three seas touch the united state? What did the North call its strategy to defeat the South by forming a naval blckade and by capturing the Mississippi River? What country does the Panama Canal pass through? Which British city does the River Dee flow through? Is the marble arch bigger than the arc triomphe? Who protects the pyramids of Giza? Where is the Hoo-Hoo Museum in Gurdon Arkansas located? Why has Google Maps named Persian Gulf as the Arabian Gulf? What is the elevation of Machu Picchu Peru? What places are animals being extinct? Is the Caribbean Sea on the east coast of Central America? Are most of Europe's largest rivers too shallow to accommodate transport vessels?

What started in the 1820s as a fur trading post along the Missouri river?