Last year, students at Pleasantdale Middle School were studying rocks when they realized Illinois didn't have one.
The kids recommended "Dolostone" and that was the winner in a survey of more than 1,200 people.
Dolostone is a form of limestone.
Congressman Sean Casten carried it forward to the floor of the Illinois house.
"It's just really cool to be able to sort of, you know, show these students that their efforts to get a law passed, that they actually did it!" Rep. Casten said.
Students at Maplebrook Elementary School in Naperville also helped push the bill forward.