I may be wrong on this, but I thought it was legal to carry as long as it was: single-edged, under 3.5" in length, and not concealed.
Of course, "concealed" seems ill-defined, and a knife clipped to your pocket and visible or carried in a leather pouch sheath may be considered "concealed" by a LEO. Here in Denver, I see a lot of people carrying 4" pocketknives clipped to their belt, and if the switchblade or butterfly knife had a clip you could conceivably carry it like that, or you could just leave it in your car.