Editing Duluth, Minnesota (section)

====Continued growth====
[[File:Duluth Ore Docks.jpg|thumb|Duluth Ore Docks and freighters circa 1900–1915|left]]

For the first half of the 20th century, Duluth was an industrial port boom town dominated by its several [[grain elevator]]s, a cement plant, a nail mill, wire mills, and the [[Duluth Works]] plant. Handling and export of iron ore, brought in from the Mesabi Range, was integral to the city's economy, as well as to the steel industry in the Midwest, including in manufacturing cities in Ohio.

[[File:Aerial transfer bridge (ferry), Duluth, Minnesota, ca.1920 (CHS-5034).jpg|thumb|[[Aerial Lift Bridge|Aerial Bridge]] ca. 1920, as a [[ferry bridge]] before conversion to a [[vertical-lift bridge]]]]
The [[Aerial Lift Bridge]] (earlier known as the "Aerial Bridge" or "Aerial Ferry Bridge") was built in 1905 and was known at that time as the United States' first [[transporter bridge]]. Only one other like it was ever constructed in the country.<ref>{{Cite web |title=shorpy.com, Photo of original bridge showing gondola |url=http://www.shorpy.com/node/4348 |url-status=dead |archive-url=https://web.archive.org/web/20170719112205/http://www.shorpy.com/node/4348 |archive-date=July 19, 2017 |access-date=July 20, 2017}}</ref> In 1929–30, the span was converted to a vertical-lift bridge, which was also rather uncommon. The bridge was added to the [[National Register of Historic Places]] in 1973.

In 1916, after Europe entered [[World War I]], a shipyard was constructed on the St. Louis River. A new workers' neighborhood, today known as Riverside, developed around the large operation. Similar industrial expansions took place during [[World War II]] as Duluth's large harbor and the area's vast natural resources were put to work for the war effort. Tankers and [[submarine chasers]] (usually called "sub-chasers") were built at the Riverside shipyard. Duluth's population continued to grow in the postwar decade and a half, peaking at 107,884 in 1960.