Early references to the American Midwest being called "America's Heartland" noted the area's strategic role as a centralized population of industrial production, as stated in The Newberry Library. As time passed, the term most commonly referred to a region associated with small towns and farms instead of busy urban areas.
The nickname "America's Heartland" wasn't associated strongly with America's Midwest until the late 20th century, specifically after the 1980s. Writers often used the term to denote a region with more traditional people who were more stable and cautious than people living in other regions. Conservative politicians felt that "America's Heartland" captured the political and moral high ground in their efforts to fight liberalism.