Two hundred years ago (assuming you cracked open this magazine the minute it arrived in your mailbox), explorers Meriwether Lewis and William Clark were leading their Corps of Discovery through a grueling portage around the Great Falls of the Missouri River. Not until July 15, 1805, did they reload their supplies on newly carved cottonwood dugout boats for the faster — but still dangerous — upriver voyage.

Since 2003, the bicentennial of Lewis' travel preparations in Philadelphia, America has been commemorating the Corps' westward journey and rekindling its spirit of discovery through exhibitions, re-enactments, ceremonies and educational Web sites. Here are some ways you can get a piece of the action: