John T. Grant’s “Indispensable” Pass

In 1839, a gifted hydraulic engineer dredged a critical link between Mobile and New Orleans.

A map showing the entrance of Mobile Bay and depicting Grant’s Pass.

The mail had to get through. Not to mention people and lumber and cotton and sundries. But during the early 19th century, travel between Mobile and New Orleans was difficult and fraught with danger. Interior roads were little better than swampy trails that were rendered impassable in foul weather, and there was, as of yet, no railroad. Alternatively, two water routes existed, one through the Mississippi Sound west to Lakes Borgne and Pontchartrain and thence overland for the short remaining distance to the Crescent City, and the other through the mouth of Mobile Bay into the open gulf to the Mississippi River and then upstream. Steamboat captains and small craft skippers preferred the Mississippi Sound route, generally safer and calmer thanks to its sheltering barrier islands. Unfortunately, a broad shoal of oyster shells, sand and mud stretching between Cedar Point and Dauphin Island made it impractical for any vessel drawing more than three feet. 

Determined to rectify the situation, the United States government appropriated $18,000 in 1828 to cut a pass through the shoal. Project engineers chose to improve an existing shallow channel at Pass aux Herons (off the northwest tip of Little Dauphin Island) and contracted the work. Among those winning bids was John T. Grant, a 32-year-old native Marylander and hydraulic engineer. Grant was an extraordinary figure. He had supported his mother and nine siblings since he was 12, working as a mechanic. He possessed an inventive turn of mind and, at 25, had invented a reliable dredge that he successfully used to improve Baltimore Harbor. After moving south in 1827, he earned respect by cutting through the Dog River and Choctaw Bars of upper Mobile Bay, thus enhancing Mobile’s maritime accessibility. 

Discerning engineer that he was, Grant had his doubts about the Pass aux Herons plan, soon confirmed when a storm filled the channel with sand. Frustrated by this circumstance, Grant shifted his attention to the other end of the route. In 1831, he designed and built a railroad that ran the five miles between Lake Pontchartrain and New Orleans. To improve the line, he invented a passing track and erected a raised station platform. Despite these achievements, he never stopped puzzling how to conquer the oyster reef that still forced larger vessels into the choppy Gulf. 

Grant approached the Alabama State Legislature in 1839, obtaining a charter to make at his own expense a cut through the reef “of sufficient depth and width to afford a good and safe inland passage for steamboats and other vessels in the trade between the waters of Mobile Bay and other places on the Gulf of Mexico.” In addition, the charter authorized him to build “all such light-houses, beacons, wharves and other buildings as may be deemed necessary to carry the object of this act into full effect.” Provided he could dredge a pass that maintained a depth of at least five feet even at low water, he could charge a toll “not to exceed fifteen cents for each ton of the registered measurement of such boat or vessel.” That was a powerful incentive indeed. 

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A view of the Dauphin Island bridge, which crosses over the area where Grant’s Pass once was.

Grant set to work immediately. He chose a site just north of Pass aux Herons, where he believed that natural currents would prevent or at least delay silting. Records do not reveal what type of dredge he used, but most likely it was either a bucket ladder dredge or a grapple dredge, both steam-powered. The former consisted of a series of scoops positioned along a swinging conveyor mounted on one side or through the center of the vessel. The crew would have positioned the craft over the desired location and swung the ladder down and started it so that the scoops bit into the bottom and brought the spoil topside, dumping it onto flats. The grapple dredge consisted of a wooden barge surmounted by a dipper that took large bites out of the bottom. Whichever machine Grant used, within a year under his capable management it had removed thousands of tons of shell, sand, and mud. 

The resulting Grant’s Pass, as it came to be known, was almost two miles long and 120 feet wide with depths ranging up to eight feet. A little lighthouse and a keeper perched on a shell island guided traffic and collected the tolls. Grant reported that during 1851 nearly half a million tons traversed this private pass, netting him $15,000 in revenue. Additionally, the mail service paid him $10,000 per annum for its vessels to use the pass, which it considered “indispensable.”

During the Civil War, the Confederacy seized Grant’s assets and constructed Fort Powell on his island to guard the pass. As a staunch Union man, this must have greatly galled him. During the Battle of Mobile Bay in August 1864, federal naval forces pummeled the fort before the Confederates evacuated and destroyed it. After the war ended, Grant tidied up the pass and resumed collecting tolls, but revenues plummeted when the Mobile and New Orleans Railroad opened in 1872. 

Indefatigable as ever, Grant kept active and served in the Alabama, Louisiana and Mississippi state legislatures. He died at the ripe old age of 90 in 1887 and is buried in Pascagoula. He left behind four children, 29 grandchildren and 78 great-grandchildren. His pass gradually fell into disuse, shoaling and silting a little more each year. The Intracoastal Waterway finally superseded it in 1914, running smack between it and Pass aux Herons. Today, the Dauphin Island Bridge gracefully crosses this history-rich area, allowing motorists to contemplate the islands and shoals and steady barge traffic amid an ever-changing color palette dictated by the vagaries of light and cloud.

John S. Sledge is working on a book about Mobile and Havana’s centuries-long shared history. 

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