The Pile–Pontoon Railroad Bridge was a floating bridge which crossed the Mississippi River

Mississippi River

The Mississippi River is the largest river system in North America. Flowing entirely in the United States, this river rises in western Minnesota and meanders slowly southwards for to the Mississippi River Delta at the Gulf of Mexico. With its many tributaries, the Mississippi's watershed drains...

 in northern Iowa

Iowa

Iowa is a state located in the Midwestern United States, an area often referred to as the "American Heartland". It derives its name from the Ioway people, one of the many American Indian tribes that occupied the state at the time of European exploration. Iowa was a part of the French colony of New...

.
Marquette, Iowa

Marquette, Iowa

Marquette is a city in Clayton County, Iowa, United States. The population was 421 at the 2000 census. The city, which is located on the Mississippi River, is named after Jesuit missionary Jacques Marquette, who along with Louis Joliet discovered the Mississippi River just southeast of the city on...

 became a major hub on the Chicago, Milwaukee and St. Paul Railway, as grain from throughout Iowa

Iowa

Iowa is a state located in the Midwestern United States, an area often referred to as the "American Heartland". It derives its name from the Ioway people, one of the many American Indian tribes that occupied the state at the time of European exploration. Iowa was a part of the French colony of New...

 and Minnesota

Minnesota

Minnesota is a U.S. state located in the Midwestern United States. The twelfth largest state of the U.S., it is the twenty-first most populous, with 5.3 million residents. Minnesota was carved out of the eastern half of the Minnesota Territory and admitted to the Union as the thirty-second state...

 was sent through the city en route to Lake Michigan

Lake Michigan

Lake Michigan is one of the five Great Lakes of North America and the only one located entirely within the United States. It is the second largest of the Great Lakes by volume and the third largest by surface area, after Lake Superior and Lake Huron...

. Initially trains had to be ferried across the river between Marquette and Prairie du Chien, Wisconsin

Prairie du Chien, Wisconsin

Prairie du Chien is a city in and the county seat of Crawford County, Wisconsin, United States. The population was 5,911 at the 2010 census. Its Zip Code is 53821....

 in order to continue their journey. A better solution was found by two men named Michael Spettel and John Lawler, who designed a permanent pontoon bridge

Pontoon bridge

A pontoon bridge or floating bridge is a bridge that floats on water and in which barge- or boat-like pontoons support the bridge deck and its dynamic loads. While pontoon bridges are usually temporary structures, some are used for long periods of time...

 to span the river in 1874. Prairie du Chien businessman Lawler took most of the credit for this invention, and made a small fortune through its operation. Marquette subsequently became home to a major rail yard

Rail yard

A rail yard, or railroad yard, is a complex series of railroad tracks for storing, sorting, or loading/unloading, railroad cars and/or locomotives. Railroad yards have many tracks in parallel for keeping rolling stock stored off the mainline, so that they do not obstruct the flow of traffic....

, which even as late as 1920 was the busiest in Iowa, employing 400 people.

However, the railroad's significance declined and the last passenger train stopped in Marquette in 1960. The pontoon bridge was disassembled in 1961.