Heights on a map are measured from sea level, the average level of the ocean. A place 100 feet above the ocean has an elevation of 100 feet. A place below the level of the ocean has a negative elevation.
Key idea
Denali in Alaska is the highest peak in North America: 20,310 feet. Badwater Basin in Death Valley, California, is the lowest point in North America: 282 feet below sea level. The highest peak in the 48 states that touch one another is Mount Whitney in California's Sierra Nevada, about 14,500 feet.
Why it works
How can land be below the ocean and stay dry? Death Valley is surrounded by mountains, so the ocean cannot flow in. The valley floor sank as the crust stretched and broke. Rain is rare, and the little water that runs in dries up in the heat, leaving salt flats.
Worked example: Top to bottom
How many feet higher is the top of Denali (20,310 feet) than Badwater Basin (−282 feet)?
- From −282 up to sea level (0) is 282 feet.
- From sea level up to 20,310 is 20,310 feet.
- Add: 282 + 20,310 = 20,592 feet.
Answer: 20,592 feet. (This uses negative numbers in context.)
Common mistake
Many people guess the highest point is in the Rockies. The Rockies' tallest peak, Mount Elbert in Colorado, is about 14,400 feet. Denali, in the Alaska Range, is almost 6,000 feet higher. Even in the 48 states, the highest is Mount Whitney in the Sierra Nevada, not a Rocky Mountain peak. Denali's federal name has been Mount McKinley since 2025; Alaska and many others still call it Denali.
Fun fact: Mount Whitney and Badwater Basin are less than 85 miles apart, so the highest and lowest points of the 48 states are close neighbors.