What are the directions from Washington to Mojave?

To drive from Washington, D.C. to Mojave, California, head southwest on I-66 W and merge onto I-81 S. Continue on I-81 S and then take I-40 W towards Barstow, California. Follow I-40 W until you reach the exit for Mojave. The total trip is approximately 2,500 miles and takes about 40 hours of driving time, depending on traffic and road conditions.