[3] Agricultural expansion and the establishment of Willmar as a division point on the Great Northern Railway determined its growth.

The first settlers arrived during the 1850s, attracted to the fertile land and an abundance of timber and game.

[9] Willmar was the site of a bank robbery by the Machine Gun Kelly gang on July 15, 1930.

They robbed the Bank of Willmar (later Otto Bremer Trust) of about $70,000 (equivalent to $1,277,000 in 2023) and wounded three people.

[10] The Willmar Memorial Auditorium, designed by architect William Ingemann, was the largest assembly hall within 70 miles when completed in 1938.

It was funded by the city of Willmar and state and federal governments as a Depression-era works project.

It contains several murals by Richard Haines commissioned by the Federal Art Project, and wood paneling in the oak doors by WPA artists.

[15] The 45° latitude line passes just south of Willmar, placing it approximately halfway between the equator and the North Pole.

Since 1989, Willmar has had a large influx of immigrants from Latin America and Northeast Africa, mostly due to the demand for labor at the Jennie-O poultry plant.

Subsequently, NBC Nightly News ran a story on Willmar's changing complexion and its acceptance of its new citizens.

[21] More national attention was received when an opinion piece about immigration and Willmar by Thomas Friedman appeared in the New York Times on May 14, 2019.

The development of Willmar benefited greatly from being situated at the junction of multiple railway lines.

From Willmar, the Great Northern Railway had lines radiating east to Minneapolis and St. Paul, northwest to Fargo and Seattle, northeast to St.