Where are the highest and lowest points in the continental United States located?

 Death Valley, California

Death Valley, California

Answer: California

"The highest and lowest elevations in the continental United States (the "Lower 48" more precisely) are both found in the state of California. Astoundingly, they are less than 88 miles (142 kilometers) apart with an elevation change approaching 15,000 feet" - Howder Family

The highest point in the contiguous U.S., 14,494-foot Mt. Whitney, is only 76 miles from the lowest point in the contiguous U.S., Death Valley.  Mental Floss