Donna, did you read post #2?

Leave the park via the south entrance and take AZ-64 to Williams. Get on I-40 west to Ash Fork and take AZ-89 through Prescott to Congress, then AZ-71 to US-60. Take that west to I-10, take that west to US-95, then take that south to Yuma. This is faster and more scenic than taking the Interstates through Phoenix