There are not as far as I can tell any Reservations in the state. However it's 2.84% Native American and they seem to be fairly evenly spread out. St. Louis is about 1.8% Native American, and Kansas City is about the state average at 2.8%, making them two of the most Native American urban areas. Springfield is almost 4% Native American.
That's significantly higher than the national numbers, especially for a state with no Reservations or concentration. Why so?
Is it significantly higher than that for other states? Provide data.
147K AIAN alone or in combination.
22K AIAN alone
of the 147K AIAN or in combination, 75K did not specify a specific tribe.
57K claim to be Cherokee alone or in combination, but only 2600 claim to be members of the Cherokee Nation. There are likely many people whose Aunt Elizabeth claimed to be part Indian. They thought she might be crazy (she had blond hair and blue eyes), but then when doing genealogical research came across her bar application in Texas, that proved she was Indian.
There were reservations in what is now Kansas (outside the United States). After Kansas became a state, some were moved to Oklahoma. The reason the Osage reservation still exists in Oklahoma, is because they took the money they received for their land in Kansas and bought the land in Oklahoma. These were mostly directly west of Kansas City, Missouri - in what is now Kansas City, Kansas and Johnson County.
Others may be an infusion from Oklahoma. If you want to eat, you have to grow it yourself, or have a job.
There does appear to be a large number of Blackfeet. There may have been effectively a colonization, where some tribal members to moved to Kansas City(?), and then provided a support network for cousins, etc. Same phenomena as there has been and are from other emigrant groups.