Between Kansas City and Sioux City, IA, the course of the Missouri River runs north-south. Following the Missouri any distance by road means taking I-29, which is right next to the eastern bank of that stretch of the river. I've had to cross from one side to the other a few times already, and it has never been a problem; there always seems to be a bridge where you need one.
The Missouri River Basin Lewis & Clark Visitors Center is located in Nebraska City, NE. If you're coming from the Iowa side of the river it's literally one of the first things that you see once you get off of the bridge. There are a few Lewis and Clark visitors centers along the Lower Missouri River, so each one needs to have something unique to offer. The Missouri River Basin visitors center focuses on how the Expedition related to the flora and fauna of the region.
At the entrance to the building there's a replica of the keelboat that was used from St. Louis to Fort Mandan (in today's North Dakota) - there seem to be a small number of similar replicas.
The sail was used when there was a sufficient wind, otherwise oars (seen on the far side) were used. When river conditions did not allow paddling, soldiers stood on the walkways along the inner side and pushed the boat upriver with poles. As a last resort men would have to get out and walk along the shore, pulling on ropes attached to the side of the boat.
On the first floor a tent is set up in the way Lewis and Clark most likely did so. Inside the tent there is an exhibit on each side. On one side the intricate process of preserving new species of animals is illustrated, and on the other side the process of preserving plant species is demonstrated. These preserves were shipped back to Thomas Jefferson from Fort Mandan. Species discovered after the winter at Fort Mandan returned with the expedition in 1806. The thought of Lewis following these procedures in the most distant wilderness is rather mind-boggling, and maybe even a little inspiring.
On the upper floor there are a few more exhibits. Here's an introduction to outdoors skills required to be part of the Corps of Discovery. You're asked to spot deer tracks, guess whether the deer was walking or running, and find scratches left by the bear on a nearby tree (to mark his territory).