The 11-mile-long Jasper Trail-Grapevine Canyon route takes hikers and all sorts of wheeled travelers -- on mountain bikes and motorcycles, or in off-road-capable vehicles -- down a series of inclines from Anza-Borrego's cooler western margins to its warm, dry interior. Despite the overall descent of some 2400 feet of elevation, this isn't exactly a Sunday picnic for anyone, especially since the November thermometer may still rise into the 80s out there. Take plenty of water along with you. If you're traveling self-propelled, convince someone to drop you off at the start and pick you up later at the finish.
The route starts at the Jasper Trail intersection, mile 6.8 on Montezuma Highway (County Highway S22), just east of the high-desert community of Ranchita. In the first 2.4 miles, the rough road traverses rolling, scrub-covered terrain, generally heading south. After passing over a rocky ridge at 2.4 miles, the road drops very sharply down a dry canyon for about 0.7 mile; then it turns north up a slope and briefly follows a ridge to avoid a narrow, rocky section of the canyon. On foot, it's easier to go down the bottom of the canyon and join the road again, saving 0.4 mile, not to mention needless elevation gain and loss.
In the next mile, the canyon is flanked by picturesque, near-vertical rock walls. After some further twists and turns and ups and downs, you arrive at the broad floor of Grapevine Canyon, a principal east-west route of travel before Highway 78's completion. Several springs (such as Stuart Spring just ahead on the route) served the needs of early automobile travelers. Centuries ago, the canyon was a favorite camping area of Native Americans. Bedrock mortars, used for the grinding of seeds and grain, can be found hereabouts.
Follow the dirt road (or, at times, a paralleling equestrian and hiking trail) down the broad floor of Grapevine Canyon. You pass Angelina Spring, recognizable by a tangle of willows. As the wide Bitter Creek Canyon comes in from the south, stay to the right as Grapevine Canyon Road veers left. The road on the right leads more directly to Highway 78, 2 miles away. Arrange to be picked up here -- mile 74.1 on Highway 78 -- just below the winding stretch of Highway 78 through Sentenac Canyon.