Construction of the works, then known as the Minnesota Steel Company (formed by USS in 1907), on over a thousand acres of undeveloped land began in 1909. The mill was located in far west Duluth near Spirit Lake, a widened stretch of the St. Louis River which flows into Lake Superior. Due to economic conditions and World War 1, it wasn’t completed until 1915. A further complicating factor was the severe climate that the engineers had to address. The structures were made of steel with concrete block walls since it was thought the air space in the blocks would lessen the impact of the cold weather in winter. A steam-heated car thawing house was also included to make sure the iron ore could be dumped.

On the “hot side,” there were two blast furnaces, each with 300,000 tons annual capacity, ten open-hearth furnaces (540,000 tons annual capacity) and a 90-oven coke battery. The liquid steel was cast into ingots and then rolled into blooms. The first bloom was rolled in the year of completion, but the output was sent to other USS plants since the merchant mill was not yet in operation. The merchant mill building had a 16-inch continuous and 8-, 10- and 12-inch merchant mills.

Also during this period USS constructed the Spirit Lake branch line to connect the mill with its railroad subsidiary Duluth, Missabe & Northern and to Superior, Wisconsin port and railroad facilities via the Interstate branch line. The latter required the building of a long rail/highway bridge across the St. Louis River. Interestingly, Northern Pacific’s truncated former Duluth-St. Paul mainline skirted the eastern side of the works, but it appears USS wanted to keep as much of the rail traffic as possible in-house.

In 1916, USS subsidiary Universal Cement Co., later Universal-Atlas Cement Co., constructed a cement-making plant northeast of the mill. The plant utilized blast furnace slag as a feedstock and had 4,000 barrel a day capacity.

Also in 1916, a rail mill began operations, but it only produced a small amount of rail since it was long past the time of railroad building in the United States. The mill was later converted to make blooms and billets.

In 1922, Minnesota Steel constructed two new “sawtooth” roof structures for rod and wire mills. One structure was attached to the merchant mill building and the other was located 300 yards away. The wire was drawn through the mill, galvanized and made into nails in 183 machines, barbed wire in 50 machines and woven wire fencing in 14 machines. The mill was capable of making 200,000 miles of barbed wire and 23,000 miles of woven wire fencing per year. The nails, of some 300 different kinds, filled 650,000 kegs (100 pounds each) on a yearly basis. The nail kegs were made on site in the cooperage shop. In 1924, steel fence posts were added to the product mix and became a key product in the merchant mill’s output. In the 1920s, production was 220,000 tons per year, well below the predicted level of 363,000 tons.

For the employees, a company town, known as Morgan Park named after New York financier J. Pierpont Morgan, was built on the northeastern side of the works in 1914. Housing was initially owned by the company, but were offered for sale in 1938. The company also supplied medical services, education and daily items in the company stores.

The Minnesota Steel Co. was leased to the USS subsidiary American Steel & Wire (AS&W) in 1932. The former company remained as a corporate entity, but functioned as a holding company no longer involved in operations.

The Great Depression of the 1930s saw both blast furnaces and the open-hearth furnaces shut down for five years, although the mills still operated with “cold” steel. During this period one of the blast furnaces was dismantled. By 1936 pig iron was flowing again from the remaining blast furnace and two open-hearth furnaces. In 1938, despite a return to economic depression, the works doubled its production to 100,000 tons per year. The cement plant briefly closed in the 1938-39 period.

In 1940, with worldwide demand for steel on the rise, the single blast furnace was running at its rated annual capacity of 300,000 tons. In 1942, a 1904 blast furnace from the Joliet, Illinois works was dismantled and shipped to Duluth. With the additional blast furnace, output rose to 655,000 tons per year. AS&W later purchased the furnace from the Federal Government in 1946. In 1951, annual production reached 715,000 tons. In 1955. a new mill was installed in the former cooperage shop to make wire reinforcement mats for concrete highway construction. In 1956, the works made five million fence posts annually and 150 million nails and 21,000 miles of steel wire weekly.

In 1964, the steel mill was formally know as the “Duluth Works” following a USS reorganization of its various business units. A problem for the mill in the 1960s was that only 20 percent of its products were finished, with the remainder shipped to other USS mills. One company executive said the company could easily make all the products the Chicago market needs in Chicago with no need for semi-finished products from Duluth.

The glow of hot metal dimmed permanently on November 13, 1971. The United Steel Workers of America's threatened strike on August 1 of that year was a major factor in the closing of the hot-side since steel users all over the U.S. had stockpiled domestic and foreign supplies prior to the strike which never occurred. The output from the Duluth Works was just not needed any more with other USS facilities chock-a-block with their own steel inventories. Another significant factor was the demand by the Minnesota Pollution Control Agency for USS to come up with a plan to reduce their pollution. USS refused to do so and decided to just shut the hot-side down.

The hot-side shutdown would permanently close the blast furnace, the remaining four open-hearth furnaces, soaking pits, blooming mill and billet mill. The rod and wire mills, fence post fabrication unit, coke ovens and cement plant were not shuttered - at least for a time. The shock to Duluth was profound as the works was the city's largest employer. Eventually about 2,500 men and women would lose there jobs. The first phase resulted in 1,600 employees being let go.

With the announcement of the hot-side closure, Minnesota politicians weighed in with offers of tax incentives to modernize the works with one desperate Duluth politician even proposing punitive taxation on taconite operations on the Iron Range to force the company to keep most of the Duluth Works open. This legislator suggested using these punitive taxes to modernize the works. But USS had no intention of modernizing the ancient blast furnaces and putting newer basic oxygen furnace technology for a mill in a small market.

The next facility to go down on January 1, 1976 was the Universal-Atlas Cement Division of USS. This plant really should have closed earlier since there was no longer a source of the key material from the blast furnace slag. Slag was even being shipped in from USS Gary Works in Indiana to keep the plant running. The plant was razed in 1978.

The end for the coke ovens came in 1979 after USS refused to spend funds to be in compliance with Federal air quality regulations. No longer would the flared coke oven gas light the night sky nor the brilliant steam clouds from the quencher at the coke ovens in subzero weather be seen in West Duluth. Spirit Lake was again quiet after 70 years of heavy industrial action. The razing of the works began on August 20, 1988.

Today, little is left of the works apart from the concrete walls of the ore yard and a few smaller buildings. However, at the plant entrance in Morgan Park a sign proclaiming a steel mill was once there still remains.

Written by Jeff Borne with assistance from Patricia Maus, curator of the Northeastern Minnesota Historical Center in Duluth, who helped in gathering information and some of the period photos of the USS Duluth Works. Additional information came from the book “Morgan Park: Duluth, U.S. Steel and the Forging of a Company Town” by Arnold R. Alanen (2007, University of Minnesota) and a 1906 "Iron Trade" article supplied by Michael Rabbitt.