What Does A Mississippi River Boat Look Like Best Marine Garmin GPS Map For Boating On The Upper Mississippi River

Best marine Garmin GPS map for boating on the upper Mississippi river - what does a mississippi river boat look like

I have bought recently installed a boat with a Garmin GPS device. I saw, and one unit is $ 900, but the monitor and the details are terrible.
I ship near LaCrosse Wisconsin, and after the GPS device, half the time I'm on the ground. Garmin says it has no software that is better. Has anyone bought an add on the card that works in the Upper Mississippi River?