ATLANTA — Fountains froze over, a 200-foot Ferris wheel in Atlanta shut down, and Southerners had to dig out winter coats, hats and gloves they almost never have to use.

The brutal polar air that has made the Midwest shiver over the past few days spread to the East and the Deep South on Tuesday, shattering records that in some cases had stood for more than a century.

The mercury plunged into the single digits and teens from Boston and New York to Atlanta, Birmingham, Nashville and Little Rock — places where many people don’t know the first thing about extreme cold.

“I didn’t think the South got this cold,” said Marty Williams, a homeless man, originally from Chicago, who took shelter at a church in Atlanta, where it hit a record low of 6 degrees. “That was the main reason for me to come down from up North, from the cold, to get away from all that stuff.”

The morning weather map for the eastern half of the U.S. looked like an algebra worksheet: lots of small, negative numbers. In fact, the Midwest and the East were colder than much of Antarctica.

The cold turned deadly for some: Authorities reported at least 21 cold-related deaths across the country since Sunday, including seven in Illinois, and six in Indiana. At least five people died after collapsing while shoveling snow, while several victims were identified as homeless people who either refused shelter or didn’t make it to a warm haven soon enough to save themselves from the bitter temperatures.

In Missouri on Monday, a 1-year-old boy was killed when the car he was riding in struck a snow plow, and a 20-year-old woman was killed in a separate crash after her car slid on ice and into the path of a tractor-trailer.