We’ve all seen how the power of social media can turn a small idea into a nationwide movement.

There’s the teal pumpkin project to help kids with food allergies enjoy a safe Halloween; the ice-bucket challenge, which generated millions of dollars to support breakthrough ALS research; and the Hawkeye Wave, a simple act at an University of Iowa football game that has raised awareness of childhood cancer.

Now a new social media campaign aims to provide food-insecure Iowans with something that many of us take for granted: a gallon of milk in the fridge.

The 10 gallon...