The Marengo Public Library is one of those libraries that was established with the help of Andrew Carnegie in the early 1900's. In 1903, an item in the Marengo Republican Newspaper noted "Marengo is the smallest town in the country to receive an offer of $10,000 for a library from Andrew Carnegie."

In 1903, a library Board of Trustees was appointed and work began on the new library. After two years of planning and building, Marengo Public Library was completed. It was dedicated on August 4, 1905 and opened to the public the next day, August 5, 1905.

The total cost of the building and furnishings was $10,683.39 of which $10,000 was contributed by Andrew Carnegie. The City of Marengo, by agreement, was to contribute $1,000 yearly for its support.

In 1905, there were 1,463 books on the shelves and a circulation of 6,668 books. The Library Board that year spent $1,226 for books and $42.00 for periodicals. There were 637 registered borrowers and the librarian's salary the first year was $212.50.

In 2003, there were 16,352 books on the shelves, as well as 1,441 video materials, and 877 audio materials. The circulation of library materials was 36,095. The Library Board spent over $9,000 for books and almost $2,500 for periodicals. There were 1,597 registered borrowers and the salary for library staff was approximately $59,500.