Why are legal notepads yellow in color?

Comic Jerry Seinfeld, former national security adviser John Bolton and the late American author Pat Conroy are just a few of its millions of devotees. We’re talking about the quintessential office supply the legal notepad. It’s simple, professional, cheap and instantly recognizable.
Part of its lure is the unwritten rule that legal notepads are for adults only; some people describe a feeling of satisfaction when they finally reach the point where they’re “sophisticated” enough to use them. After all, legal pads equal important business.
The most recognizable characteristic of a legal notepad? The yellow color. But why are they yellow? Good question. To answer it, though, requires a brief explanation of its history first.
The legal pad was invented by a paper mill worker, Thomas Holley, in Massachusetts around 1888. Holley came up with the idea of collecting the tons of paper scraps off the floor of the mill and stitching them together to make pads of paper.
He was apparently irritated that he had to pick up paper scraps that littered the floor, and before long, his paper pad invention was a hit. Though the paper in his pads was originally white, they were so popular, Holley was able to quit his job at the mill to form the American Pad and Paper Company, or AMPAD.
Now back to why legal pads are yellow. There are lots of theories about that, but no one really knows for sure. Some say they were yellow from the beginning. The theory is that because the pads were originally created using pieced-together scraps, they looked cheap and low quality. So Holley dyed them to make them a classier, more uniform yellow.
This sounds reasonable, but it’s probably not true. Dyeing paper at that time would have been prohibitively expensive and not worth cutting into profits.
Some accounts are from a little later — probably after Holley’s time. They include the belief that yellow is easier on the eyes because it doesn’t create as much glare as white, and thus, yellow paper was the obvious way to go.
Others hypothesized that yellow paper was beneficial because it didn’t show age like white paper. Still some believed that Holley’s pads went from white to yellow because yellow stimulates the mind, including areas of recall and creativity.
While we may not know the real answer why they’re yellow, we do know the origin of a legal pad’s margin. Around 1900, a local judge asked Holley to add a vertical line down the left side of the paper to create a margin where he could make notes. Those margins — also known as down lines — are always red and drawn 1.25 inches (3.1 centimeters) from the left edge of the page.
Aside from the yellow paper, blue lines and a gummed, tear-off top, the red margin is the only requirement for a pad to qualify as a legal pad. In other words, yellow, blue, pink or purple paper, without the red margin, it’s not a legal pad.