In January 1937, while covering the disastrous flooding of the Ohio River in Louisville, Kentucky for LIFE Magazine, Margaret Bourke-White captured an image that quickly became famous and eventually rose to become an icon of the Great Depression.

The photo features a simple but sharply ironic juxtaposition: African-American flood victims line up for relief below a billboard with a beaming white family proclaiming WORLD’S HIGHEST STANDARD OF LIVING.

Though Bourke-White’s image was one-of-a-kind, the billboard was not. It was one of thousands erected across the country as part of a years-long propaganda campaign by the National Association of Manufacturers (NAM).

Founded in 1895, NAM became a harsh critic of labor unions and government regulation in the early years of the New Deal. In the 1930s, NAM launched a wide-ranging publicity effort involving millions of cartoons, newspaper columns, leaflets, films, and more, preaching the virtues of free enterprise and the dangers of state intervention.

Some of the billboards claimed WORLD'S SHORTEST WORKING HOURS as the result of unfettered markets, rather than decades of union struggle and government regulation.