Missouri's flag has some good points, but is in need of a tune up (Sorry, I had a couple car references left from the Michigan post):
The tricolor design is little used in American state flags and is used to great effect on this one. It has the busyness of the seal in the center, but the fact that it is flanked by bears makes it cooler than most others. Even the ring of stars looks good, referencing Missouri's position with a simple, appealing pattern. My biggest concern is the similarity with the flag of Paraguay:
So what is to be done? Missouri has had this design since 1913 and 98 years seems like long enough. Luckily, Missouri's cities have some fine flags from which to draw inspiration, particularly Jefferson City and St. Louis:
In case you couldn't tell, this is the flag of Jefferson City, the state capital. It shares the color scheme and ring of stars with the state flag, but throws in the map of the state and rivers, along with the state capitol replacing the seal. I like this flag, and with a few minor tweaks it could serve the entire state:
Simple fixes, just remove the text and the capitol and it suites the whole state perfectly.
I am a fan of maps on flags, though many other are not. That could spring from a love of maps, but I think they add a real sense of place and an immeadiate connection between the flag and whereever it may represent. This can range from the exact representation of Cyprus on their flag to the highly stylized flag of The Gambia. I can understand the issues involved in exactly mapping an area on a flag. What if the map is wrong or includes areas in dispute (see Cyprus again)? Missouri could be a challenge in this regard because the Mississippi River occasionaly changes course, shifting parts of the state to the other bank (take a close look at the river border of Louisiana, Mississippi, and Arkansas sometime and you'll see what I mean). Though such areas are generally very small, there's no reason to risk it, so I'll scrap this particular design and try for a more stylized one:
The flag of St. Louis is a great example of this. It represents both the history and geography of the city with a very simple pattern. The fleur-de-lis represents the city's French history, while the wavy blue lines denote the confluence of the Missouri and Mississippi Rivers. This can serve as the template for the state, I just need to shift the symbolizism around a little:
Here is my suggestion for a new Missouri flag. It provides a link to the states French and American history (red, white and blue) and a basic map of the state, simplifiing the courses of the Mississippi and Missouri Rivers, as the former flows along the eastern border of the state and the latter bisects it from west to east. Specific symbols of Kansas City, St. Louis, and other locals could be added, but I think it works best without those additions. It has clean colors and design and packs a lot of meaning in a simple image.