State departments of transportation and often cities and counties collect information on traffic volume, and many make it available. You can use the numbers to see where people go in different areas, how many vehicles pass through certain intersections, etc. The data can help you decide good locations for storefronts and where to place billboards.
The state traffic map for Missouri includes major urban area traffic patterns. Also check with a city's planning department or police department to see who has traffic data. Surf their website and make a phone call if needed to track down the data.