Recycling cardboard should be easy, and some 77% of cardboard is recycled, according to the EPA （Environmental Protection Agency), not all cardboard can be recycled.
There are two kinds of cardboard.
Corrugated cardboard — used to make brown packing boxes — is identified by the wavy inner layer of cardboard, making it a kind of three-layer sandwich of cardboard.
Paperboard — (sometimes called chipboard) is a single layer of gray cardboard that’s used to make cereal boxes, shoeboxes and other packages.
In most cases, cardboard can be easily recycled, though recycling collectors often require that cardboard boxes be flattened before collection. Tape, labels and other items can be left on the cardboard (they’ll be removed at the recycling center).
Cardboard and paperboard can’t always be recycled, however. Pizza boxes and other food containers are often contaminated with grease, rendering them useless for recycling. Other cardboard containers are coated with wax or other substances to give them more strength when wet — these usually can’t be recycled, either. Juice containers, milk cartons and some produce boxes are resin- or wax-coated and are not always recyclable.