This is a tiny pony truss. I have not done a field visit, but it may well be older than the Kansas default date of 1910. A newer bridge of this small size would have likely been a simple beam structure.
Marshall County still has some bridges that would be worth visiting if someone is in the area. I doubt that I will be there soon.
Ha....this one IS tiny, 30" tall - very cool, often say what a beautiful spot a bridge is located in, but this one is unbelievable - remote, in the gorgeous Flint Hills, amazing.