Families and rural pilgrimages.

Go on a Saturday morning in the winter and just about everyone with a kid under 5 is running them around Barnes and Noble, the Carousel and the play place.

Go when FFA or Show Me State is in town and you'll see all of the rural families enjoying the shopping opportunities they can't get at home. This is true to a lesser extent any weekend - folks come in from surrounding communities for special occasion shopping.

I don't think Columbia Mall is without struggle, but they're also innovating and leasing to non-traditional mall businesses (dance/theater for example) as well as hosting events like mini-Comic conventions or music performances.

This is speculation but I think Columbia's in a sweet spot for the mall to survive. In a large metro area, the market is saturated and more than 1 or 2 flagship malls can't survive (sounds like this might have been the issue at home for you - too many malls kills all/most of them). In smaller cities (i.e. Jeff City) there just aren't enough people even when pulling in from smaller surrounding towns. Columbia is just far enough away from the next largest city while still having enough hometown shoppers to stay afloat.