WISCONSIN -- The world's largest collection of 1929 and 1930 Nash Motors automobiles exists not in a museum, but rather entombed in the frigid depths of Lake Michigan.

The cars, 268 of them, are lashed in rows inside and crumpled in a heap next to the wreck of the SS Senator, a Great Lakes steamship that rests for eternity in an uncharted sinkhole about 15 miles east of Port Washington, Wis.

The Senator, which sank during the final days of the Roaring Twenties as the country was plunging into the Great Depression, sits upright nearly 450 feet down; so deep that few, if any, divers will ever see her in person. Her collection of vintage autos once bound for Detroit join the pantheon of ships, airplanes, submarines, train cars and other vehicles of yesteryear that populate the bottom of Lake Michigan.

"Those cars on the inside are in pretty good condition," said Tamara Thomsen, a maritime archeologist and shipwreck diver with the Wisconsin Historical Society who surveyed the Senator wreck in November.

In April, the wreck was added to the National Register of Historic Places; one of nearly 150 U.S. shipwrecks on the historic list. Coincidentally, the Senator sits within the boundary of a pending National Marine Sanctuary that will become the second such protected area of shipwrecks within the Great Lakes.

The ship sank on Halloween, Oct. 31, 1929; mere days after the infamous Black Thursday stock market crash that threw the country into an economic spiral.

She is the lesser known among a trio of Lake Michigan shipwrecks that week. On Oct. 22, the SS Milwaukee train car ferry sank off Milwaukee with all 52 hands. On Oct. 29, the SS Wisconsin steamer sank off Kenosha with about 18 lost.

The Senator left Kenosha two days later, laden with $251,000 worth of brand new cars from Nash Motors, a Wisconsin-based automaker founded by former General Motors president Charles W. Nash. The company had just begun offering a new 8-cylinder engine model that month and the 1930 models incorporated a 133-inch wheelbase -- the longest Nashes built to date.

The cars were bound for dealerships across Michigan and the Midwest. Nash filled a niche between luxury cars like a Packard and economy models like a Ford. The cars would likely have sold for $1,000 to $2,000 to professionals like a doctor, lawyer or bank manager looking for a practical, higher-end ride.

"You kind of had to want a Nash," said Jay Follis, marketing director at the Gilmore Car Museum in Hickory Corners, Mich. "Other companies sold similar vehicles for less, but Nash had a great reputation."

It was foggy the night the Senator steamed northward. About 10:20 p.m., the ship's crew heard the fog signal of another steel bulk carrier, the 420-foot Marquette, bound for Indiana Harbor with 7,000 tons of iron ore from Escanaba.

A late 1920s Nash Motors automobile on display at the Rambler Ranch classic car museum in Elizabeth, Colorado.

Despite visibility about 100 feet, Captain George H. Kinch sailed the Senator at full speed, sounding fog signals as the 33-year-old ship cut through the pea soup. According to period news accounts, the Senator sounded a passing signal of one short blast -- indicating a port-to-port passage -- and the Marquette acknowledged this signal by returning one short blast of her own.

Suddenly, the Marquette appeared out of the fog only a few hundred feet from the Senator's port side. Despite Captain Kinch's frantic attempt to avoid the inevitable collision by throwing over the rudder, the Marquette struck the Senator just aft of amidships on her port side. As the Marquette pulled free, water began rushing into the stricken ship, causing an immediate port side list.

"SOS; collided with SS Marquette 20 miles east of Port Washington; sinking fast," was the first distress message over the radio at 10:30 a.m.

The ship settled quickly at the stern, the bow lifting high into the air. The Senator slipped beneath the waves just 8 minutes after the impact. Several of the 28 crew members leapt onto the Marquette immediately after impact. A nearby tugboat that heard the crash plucked another 15 from the icy waters. Ten men died.

William Dorsch, 19, was the youngest survivor.

"I was down in the stoke hole when the warning came," Dorsch told the Milwaukee Journal. "I ran up the stairs, found a life preserver and then jumped off. Man, there wasn't much time to do anything else. It's a big thing for us that tug came along when it did or we wouldn't have lasted much longer."

Although the Marquette was badly damaged, the ore boat limped to Port Washington, where its captain met jeers for not doing more to help the Senator's crew. No life rings were thrown, ladders lowered or lifeboats launched.

An investigation report later found both captains equally at fault for steaming at high speed in dense fog. Ship owner Nicholson Universal Steamship Company of Delaware later honored Captain Earl Godersky of the tug Delos H. Smith and his three-man crew for their fog-enveloped rescue.

In 2005, Paul Ehorn and Rob Polich claimed to have discovered the wreck of the Senator, but it wasn't until November that Thomsen was able to wrangle together an ROV (remotely operated vehicle) from Duluth, Minn. and survey the wreck using coordinates from the Wisconsin Department of Natural Resources.

The team found the Senator's pilothouse and bow cabins in great shape, not blasted off by the force of air escaping the ship during its death throes. The cars stored on deck lay in a crumpled pile off the starboard stern. Inside, the ROV found autos lined in neat rows of three in one of the holds.

Historical records available don't say whether the Senator carried 1929 or 1930 model Nash coupes or sedans. Thomsen and researchers hope to answer that and other questions about early Wisconsin automobile manufacturing as well as gain insights into Great Lakes historical vessel construction and shipboard life.

As for Nash Motors, the company went on to make the popular Nash-Healey sports car and Rambler compact. Nash merged with Kelvinator Corp. in 1937 before restructuring into the American Motors Corporation in 1954 with George W. Romney, who later was elected governor of Michigan, as chairman. Chrysler acquired the company in 1987 and rebranded its models as Jeep-Eagle.

"I think a lot of other companies, had they lost 260 cars and had the stock market crash in the same month, they would have locked the doors," said Follis. "It was only through the reputation of management Nash was able to keep going."

"I doubt, if you looked at their books, they made much of anything that year," he said. "I think a lesser company would have been done."

Garret Ellison covers government, environment & the Great Lakes for MLive Media Group. Email him at gellison@mlive.com or follow on Twitter & Instagram