Moved from ID Request.

...and the slightest traces of spots on the elytra strongly suggest this is Cicindela obsoleta with highly reduced maculation. I don't think nigrocoerulea occurs in that part of Oklahoma.

Based on locality, this should be subspecies vulturina. While black individuals are known, linear white or yellow elytral markings are almost always present. Even in individuals with reduced maculation there is usually an oblique, narrow line at the middle and/or apical third of the elytra. This one is probably about as black/immaculate as they come.

This is another example of the tendency to overstate length when estimating from memory. The maximum length for this species is 20 mm. My general impression is that non-specialists tend to overestimate length by up to about 2-fold with impressive species such as this. I would urge folks not to indicate size unless they have actually measured the specimen, can properly deduce this from the mag factor on their lens, or have good working familiarity with the group.

p.s. those "white markings" on his forlegs are actually pads on the bottom of the tarsi, indicating that it is a male individual.

but this might be Large Grassland Tiger Beetle - Cicindela obsoleta. You didn't mention size