An hour north of St. Louis the Mississippi almost doubles in size. Joined first by the Illinois River and then the Missouri. The area has bluffs, woodlands, and wetlands. A good starting point is the Pere Marquette State Park boat ramp. Shoving off you are on the Illinois River. As you head south the Mississippi joins you on the right a little ways north of Grafton. A few interesting eddys along with perhaps a standing wave or two as the two rivers join. Depending on the river level there are often some nice sand bars in the area.
Along the way tugs and their tows pass up stream and down. On weekends there is a flotilla of pleasure boaters who are surprisingly friendly. Time the ferryboat so that it doesn't get in your way or vice versa.
Grafton is home to the only kayak outfitter in the St. Louis area Grafton Canoe and Kayak Rental. Directly behind the Grafton Boat Ramp these folks are very helpful with rentals and transportation.
Pere Marquette to Grafton can be done in around two hours by an experienced paddler or stretched into a nice day with lunch and sunbathing. For longer trips there are a variety of put ins further up the Illinois or you can continue down the Mississippi to Alton, the confluence with the Missouri and jump off site for Lewis and Clark, the Chain of Rocks Rapids, or all the way down to the St. Louis Riverfront at the Arch.
As you continue south from Grafton with majestic bluffs on your left and wetlands on your right you will pass the historic town of Elsah and arrive at Alton. Just below Alton is the lock and dam. Depending on the operator and your nerve you can pass through the lock or portage around.
Below the locks a short way the Missouri enters from your right. Watch for eddys and cross traffic. On your left is the location where Lewis and Clark camped while they got ready for the push up the Missouri. A visitors center is nearing completion.
Below this point a ship canal takes off on your left. The river takes the left down past the I270 bridge and the old Rt 66 Chain of Rocks Bridge. Just below these bridges is the Chain of Rocks Rapids. An accessible portage and take out is on the left on Choteau Island.
The old Rt 66 Chain of Rocks Bridge is now open only to pedestrians and bicycles. A chance to walk across the Mississippi. Quite a trip.