How Low Can it Go?

On January 29, 2013 · 2 Comments

I stumble across the most fascinating bits of information in unexpected places. It happened this time as I examined the unusually-wide median strip between the eastbound and westbound lanes of Interstate 8 in southern California. I learned of a nearby oddity further down the highway while reviewing various roadfan websites.

A motorist will encounter the lowest overland elevation in the entire Interstate Highway System just to the east of the extreme central reservation I’d discovered earlier. It is listed as 52 feet (16 meters) below sea level by the U.S. Government’s Federal Highway Administration.

It’s not the lowest elevation of any road of any type within the U.S. — that’s Badwater Road in Death Valley which provides access to the lowest public restroom in North America (~ -282 ft, -86 m) — just the lowest natural point of elevation in the Interstate Highway System. It’s still pretty impressive, though.



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This happens in the vicinity of Exit 107 where I-8 crosses the New River. Notice the channel. The road dips down here as it crosses the river over a short bridge. Where, I wondered, could the New River be flowing if it was already more than fifty feet below sea level here? Certainly it would not be flowing to the sea. It much be part of an endorheic basin, and indeed that is the case.

The New River begins in Baja California, Mexico where it’s known as the Río Nuevo. It passes through the wonderfully conjoined portmanteau cities of Mexicali and Calexico. From there it flows under the I-8 bridge west of El Centro, and on to the Salton Sea. The surface elevation of the Salton Sea is -226 ft (-69 m) so whatever flows along the New River won’t leave the Salton Sea on its own unless it’s able to evaporate.



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That’s a problem. This Street View image from the point of lowest Interstate elevation shows one of the most polluted bodies of water in the nation. Sewage, pesticide-laden agricultural runoff, and industrial waste from businesses located along the ditch then dump into a basin without an outflow. Toxins and pathogens collect in extreme concentrations, creating a most foul situation. Those driving at high speed along I-8, crossing this point of lowest elevation, likely never consider the drawbacks of this dubious honor.

Let’s put one more asterisk onto the claim. There are other places along the Interstate Highway Systems with a lower elevation. However, they are located in tunnels. A similar situation exists in Canada.



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The Intertubes claims that the Fort McHenry Tunnel carrying I-95 traffic through Baltimore, Maryland represents the absolutely lowest Interstate elevation at 107 ft (33 m) below sea level. It passes in close proximity to historic Fort McHenry, as implied by the name, the battlefield site inspiring the Star Spangled Banner. It then drops below Baltimore Harbor. I’d post a Street View image except that the interior of a tunnel isn’t exactly the most exciting scenery available (check for yourself if you must).

While the exalted position of the Fort McHenry tunnel seemed to be conventional wisdom for the cyberspace masses, it was not the only candidate offered. I discovered numerous other claims. I could not, however, nail-down a definitive source. Another option included the I-93 Thomas P. "Tip" O’Neill Tunnel, part of the Big Dig project in Boston, Massachusetts. The I-64 Hampton Roads Bridge-Tunnel in Virginia was also mentioned frequently. I know we have several roadfans who read 12MC regularly so hopefully someone can provide a proper citation and we can put these issues to rest. I’ve driven through all three of these tunnels so I’m covered no matter how it turns out. Funny, I never realized I was experiencing a true geo-oddity during any of my transits.

I’ve never driven on I-8 through California though. I look forward to experiencing both the wide median and the lowest overland elevation someday.

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12 Mile Circle:
An Appreciation of Unusual Places
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