Flatiron, formerly known as Yellow Creek or Flat Iron City, is a ghost town in Lawrence County, South Dakota, United States.

In 1894, the town began to be staked out, but was not yet fully founded; when the area boomed around May 1896, a series of large buildings and small cabins, including a two-story boarding house, were built.

The Chicago, Burlington & Quincy Railroad ran through Flatiron, and the town was home to the Wasp No.

The main railroad was eventually extended to the mill; however, the grade was so steep that the cars had to be hauled up by a winch.

In 1927, a powerful flood resulting from heavy rain caused this accumulated tailings to slump.

The tracks were not uncovered until around 1974, when Lead and Deadwood, two neighboring towns, began to use the tailings to sand icy roads during winter.