The cache is NOT at the posted coordinates.
The posted coordinates are near one of the stops of the "Lincoln Highway - Elk Grove to Woodbridge" Adventure Lab, one of many LINCOLN HIGHWAY themed Adventure Labs in California.
At all ten Adventure Lab locations, you will see a bonus hint (i.e. X = 7) after correctly answering the question. This will help you solve for the final coordinates (N 038° AB.CDE, W 121° FG.HJK) for this cache. You can check your solution on the geocaching cache page.
The Lincoln Highway was the first transcontinental road for automobiles in the United States. It was established in 1913, spanning 3,389 miles, from Times Square in New York City to Lincoln Park in San Francisco. In California, portions of Interstate 80, most of U.S. Route 50 and most of old U.S. Route 40 are alignments of the Lincoln Highway.
For more of our favorite caches that we have created and placed in California, Nevada, Washington, and Hawaii, check out this bookmark list: JoyfulNomad's Favorite Owned Geocaches