For hundreds of years, most paper was made from rags. In the 1800s, people learned to make it from wood pulp. Then wood became the main ingredient. Papermaking spread from China to the Middle East by the 700s and to Spain by about 1150. After that it spread through the rest of Europe.

The first paper mill in what is now the United States was built in Pennsylvania in 1690. At a mill, workers take the bark off the logs. Then the wood is cut into small chips. Paper can be made from many kinds of trees, such as spruce, pine, fir, aspen and birch.

Some pulp is made by pressing logs against huge spinning stones. This grinds the wood into fibers. Other pulp is made by cooking chips with water and other things until they get soft. Paper made with long fibers is stronger, so mills like spruce and other cone-bearing trees.

Pulp can be bleached to make it lighter and whiter. Mills mix chalk or clay into the pulp. Some paper is coated with a thin layer of fine clay. The clay makes the surface smooth and glossy, so pictures print well.

On a paper machine, wet pulp is poured onto a moving belt of fine mesh. The water drains away. The wet sheet is squeezed between rollers. Then it is dried with heat. A big machine can have 40 to 70 steam-heated drums. At the end, calenders make the paper smoother and flatter.

A watermark is a pattern pressed into paper while it is wet. You can see it when you hold the sheet up to the light. Mills also add a coating called size. Without any size, paper soaks up ink like a blotter.

Paper mills burn bark and other leftovers from making paper. This makes steam and power for the mill. Old paper can be made into new paper, which is called recycling. In 2018, paper and cardboard were the largest single part of the trash that Americans threw away.

Words to know

• pulp: soft wet mix
• watermark: hidden pattern
• calenders: smoothing rollers
• size: paper coating

The short version

Paper is made of tiny fibers, mostly from trees. At the mill, bark is taken off the logs, the wood is cut into chips and cooked into a soft, wet pulp. The pulp is spread on a screen, the water drains out, and the sheet is pressed and dried.

Quick facts

• Paper is made of tiny fibers, and most come from trees.
• Paper can be made from spruce, pine, fir, aspen and birch.
• A paper machine can have from 40 to 70 steam-heated drums.
• Papermaking spread from China to the Middle East by the 700s.
• Paper and cardboard make up about a quarter of the trash Americans throw away, as of November 2026.