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Barrels of oil await shipment at Oil Creek, PA, circa 1864.

The American petroleum industry first began when Edwin L. Drake drilled his well near Titusville, in Venango County. Striking crude oil on August 27, 1859, Drake was the first to demonstrate that drilling could produce a steady supply of oil. Hundreds soon followed Drake into the Oil Creek Valley in hopes of becoming rich. Overnight, it seemed, the commercial possibilities for fuel and lubrication became clear to many speculators, and the great Oil Boom was on. Real estate prices in the area soared from $4 an acre to up to $7,000.

In 1859, Drake's well pumped two thousand barrels; by 1880, the area produced twenty-six million barrels, and the industry faced a major obstacle: How could it transport millions of barrels of crude to refineries and markets?

Densmore wooden oil tanks on a railroad flat car, Drake Well Museum, Titusville,...

In the 1850s, Venango County was a farm region with few roads, no railroads or canals, and streams that were not always navigable. At first, much of the oil was loaded onto skiffs and barged out on Oil Creek and other small streams. For an exorbitant fee of $4 a barrel, teamsters would haul wagonloads of barrels to the nearest railheads, twenty or thirty miles away. Realizing the money to be made, railroads soon extended their tracks to the county and its wells, with the Oil Creek Railroad reaching Titusville in 1862. The new branch line carried oil north to Corry, where it could travel east or west to refineries on existing rail lines. By late 1871, the Warren and Venango, a predecessor of New York Central, also built a line into Titusville.

Once the railroads arrived, oil producers could load dozens and then hundreds of barrels, each of which held forty-two gallons, onto railroad boxcars or flatcars. The teamsters were soon out of business. But the expense, delay, and the high cost of loading oil into barrels (which cost about $3 each) led the industry to push for a better means of bulk transportation. The railroads, however, were unenthusiastic about developing bulk cars for moving petroleum, for specialized cars were designed only to move liquids. Unsuitable for moving other goods on return trips, oil cars generated no railroad revenue on the backhaul. If tank cars were going to be built, oil companies would have to lead the way.

Discarded Densmore oil tanks, circa 1875.

During the Civil War, several inventors patented designs for mounting oil vessels on a flatcar or inside a boxcar. None got off the drawing board, however, until the Densmore brothers - the quiet, almost unknown Amos and his boisterous older brother James -devised a rather simple plan for placing two vertical vats with lids on a flatcar, each capable of holding 1,700 gallons.

New Yorkers who had migrated to Wisconsin, the Densmore brothers were drawn to northwestern Pennsylvania by the great oil boom of the early 1860s. On July 18, 1863, they started the Densmore Oil Company, with headquarters near Meadville. Their first two tank cars were tested around September 1, 1865, and the government granted them a patent on the design on April 10, 1866. Railroads were soon moving hundreds of oil-vat cars.

The benefit of such cars to the oil industry was immense - it cost $170 less to ship eighty barrels of oil from Titusville to New York in a tank car than in individual barrels. But the Densmore vat cars had some major flaws. They were unstable, top-heavy, prone to leaks, and limited in capacity by the eight-foot width of the flatcar. Within a year, oil haulers shifted from the Densmore vertical vats to larger, horizontal riveted iron cylindrical tanks, which also demonstrated greater structural integrity during derailments or collisions. The same basic shape is still used in modern tank cars today.

Oil cars under full moon

Although the Densmore vat car business went from boom to bust in the blink of an eye, the demand for cylindrical tank cars went on a meteoric rise. In the late 1860s, when industrialist John D. Rockefeller began to assemble an oil empire under the banner of the Standard Oil Company, he also began to monopolize railroad tank cars in America. By 1888, Rockefeller owned or controlled some 5,600 of the 6,100 tank cars then in service - a monopoly that allowed him to set his own terms for producers, refiners, and railroads.

Rockefeller's dominance of the American oil industry attracted the attention of one of the first muckraking journalists of the Progressive Era, Erie County native Ida Tarbell. Her stories about Standard Oil in McClure's Magazine ran in nineteen parts from November, 1902 to October, 1904 and were eventually republished as a book, The History of the Standard Oil Co. Rockefeller responded by calling her "Miss Tarbarrel," but her charges were largely correct. Readers were outraged at the revealed greed and power, and demanded that the federal government enact reforms. In 1911, the government forced a breakup of Standard Oil; Rockefeller was forced to divest his Union Tank Line, the flagship of his tank-car operation, which then became the Union Tank Car Co. Within a decade, other operators either grew or entered the field, including General American Tank Car Co. and North American Tank Car Co.

In 1867, the Densmore brothers left oil country. Just a few years James Densmore banked his last savings on a newly invented "typewriter," the success of which can be largely credited to his efforts. Biographies of the Densmores - and even their personal papers now residing at the Milwaukee Public Museum - all refer to their work on typewriters, but make no mention of their pioneering work in railroad tank car design.

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