The main park road angles from the south entrance to the west entrance and neatly bisects the park into two halves. The main road is about forty miles long and the visitor van stop anywhere and start hiking in any direction. There really are no restrictions on hiking--just watch out for rattlesnakes.
From Indio and cathedral City, head a west on I-10 through the lush Coachella Valley for about 30 minutes, and exit onto Highway 62 East just past North Palm Springs. This is
the approach route to four of the five main park entrances, the first of which is reached at Yucca Valley, 17 miles from the I-10/ Highway 62 split.
Highway 62 from Palm Springs leads to the West Entrance, near the town of Joshua Tree, and the North Entrance is close to the Oasis visitor center (see map above). There is another entrance and visitor center at Cottonwood, seven miles north of Interstate 10.
From Ontario airport it is about a 1-1/2 hour drive, From Palm Springs it is about 30-45 minutes, and from Las Vegas it takes a little over 3 hours. I made all three of these trips during my visit with a rental car.
It only costs $10 to enter the park. We used the North Entrance, right down from the Oasis Visitors Center. Be sure to stop in - the rangers are very helpful when it comes to planning your trip. Also, bring plenty of water, as there is none in the park. Bathrooms are near all of the main campsites. Some are port-o-pottys, others are in in small concrete new buildings. Those do have toilet paper, the port-o's I don't remember, as I had no need for TP when I used them.