A national organization involved, Food and Water Watch, asked people to sign letters to send to Illinois' lawmakers calling for labeling. They say genetically modified organisms, also called GMOs, are bad for people and the environment.
"We're in the middle of corn and soy country and that's why we're here. Because people don't know what's in their food and they have a right to know what's in their food," said Lois Kane, a volunteer coordinator with Food and Water Watch.
Others argue GMOs have created a better food system and eliminated the need for pesticides. The GMO-labeling bill will be up for a vote in the fall.
Copyright 2015 Nexstar Broadcasting, Inc. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.