Fact Check

Botts' Dots

How Botts' Dots, the rounded raised markers on California roads, came to be invented.

Published June 20, 2001


Claim:   The rounded raised lane markers installed on California roads, Botts' Dots, were named for their inventor.


Origins:   They may be "raised pavement markers" in the parlance of the dictionary-keepers, but they are Botts' Dots to anyone who drives over them. These rounded, raised plastic, ceramic, or polyester domes that serve to mark off freeway lanes are almost exclusively known by their pleasing-to-the-ear nickname rather than by their more proper (and descriptive) designation.

Botts' Dots are named for their inventor, Elbert Botts, a chemist who worked for Caltrans (California Department of Transportation) in the 1950s as chief of the highway-pavement division. They were designed to enhance painted lines used in designating freeway lanes. Repainting these lines season after season was proving to be both costly and dangerous (the more often Caltrans workers were exposed to vehicles zooming by, the more often there would be a mishap), thus an alternate solution was


Caltrans experimented with better, more reflective, paint but was unable to overcome the substance's inherent shortcoming of not being reflective enough in the rain or when a layer of water obscured lane markings after a rainfall. Improved paint wasn't the solution — it was time to think outside the box.

Botts began to tinker with rounded lane markers, his work culminating in 1955 in the invention of what would become a ubiquitous part of California highways, the Botts' Dot. Use of the embedded raised domes resulted in a reflective lane separation that was visible day and night, rain or dry. Its inventor always swore inventing the dots was the easy part — much more challenging was coming up with the glue to hold them in place year after year. (At first, Botts favored attaching the dots to the roadway with steel spikes but soon realized a spike that shed its dot would become a hazard lying in wait of a plump unsuspecting tire.)

The glue was perfected in the early 1960s, but the first Botts' Dots weren't installed until 1966 on Interstate 80 around Fairfield and on Highway 99 near Fresno. Elbert Botts did not live to see his brainchild make his name a household word — he died in 1962 long before any fame was associated with him.

A persistent bit of lore attaches to Botts, that he sold his idea to Caltrans and became a wealthy man by wisely insisting on payment of a small royalty per dot installed. That is untrue: Botts was the head of the Caltrans department charged with devising solutions to the marking of freeway lanes problem. This was no lone inventor slaving away in a basement laboratory who devised a killer app, sold it to a company in desperate need of it, and suddenly found himself living in the lap of luxury as the royalty checks kept rolling in. Rather, this was a man who worked a 9-to-5 job at Caltrans battling all manner of problems associated with pavement and lane markings.

Botts' Dots come in two types, round and square, and in several colors. Most are white, center markers are amber, wrong-way markers are red, and fire hydrant markers are blue. On most multi-lane freeways, Caltrans uses four white round non-reflective dots in a row, interspersed every 48 feet with a reflective square, along the painted stripes dividing lanes.

In 1997, there were some 25 million Botts' Dots in California. They can last more than ten years on some stretches of roadway but in others have to be replaced after only a few months' wear.

Botts' Dots provide an additional benefit unforeseen by its inventor — driving over them produces a ka-thump! ka-thump! ka-thump! sound that swiftly captures the attention of motorists drifting out of their lanes or off the highway. Because of this, they are installed on the outer edges of roadways known for their incidence of highway hypnosis as well as on the lines dividing one lane from another. Many a sleepy or distracted motorist has been saved from disaster by the alerting ka-thumps! of a sequence of Botts' Dots under their wheels.

Barbara "dot common" Mikkelson

Last updated:   20 May 2011


    Haldane, David.   "Dots' Demise Denied."

    Los Angeles Times.   7 March 1997   (p. B1).

    Johnston, Steve.   "Botts Dots? Here's All There Is to Know."

    The Seattle Times.   9 July 1997   (p. B3).

    Kerr, Jennifer.   "Rumbling Botts' Dots Are Freeway Lifesavers."

    Los Angeles Times.   6 October 1985   (p. B5).

    Lemke, Caroline.   "Tales from the Freeway: Lane Lingo."

    Los Angeles Times.   9 July 1992   (North County Focus; p. 2).

    Rubenstein, Steve.   "Caltrans Plots to Erase Lots of Botts Dots."

    The San Francisco Chronicle.   18 January 1997   (p. A13).

    Associated Press.   "Bumps in the Night."

    The San Diego Union-Tribune.   24 September 1985   (p. A14).