597 miles. How you get there is you go up to I-70 via I-435 or SR-7 and then you take I-70 WEST to Denver.
Which is a very good plan for Olathe, Kansas. Olathe, Colorado is located in the Grand Junction area about 288 miles west of Denver. Both raise corn. The Kansas corn is fed to livestock. Olathe, Colorado sells sweet corn for human consumption as Corn on the Cob and it is available at farmer's markets and at your local grocery.