I have lived my entire 57 years in the D.C. area and during all of that time our so-called "Yellow" Cabs have been painted orange and black, and not yellow. Can you explain why?

Bruce N. Shulman, Silver Spring

Trying to answer this question is like trying to get to the center of an onion. You peel and you peel and all you find is riddle wrapped in enigma. Plus, your eyes are watering.

Answer Man can only speculate on this age-old question, a question that Post columnist Bill Gold asked in 1969 and Bob Levey asked in 1982.

Neither answered it. No one connected with the company has any idea, either.

Not Vaughn Williams, who has owned D.C. Yellow Cab since 1995. Not Vaden Pitts, who owned it for 20 years before him. Not Ralph E. Ruth Jr., who in a 1948 Yellow Cab pamphlet is celebrated as the company's youngest driver and who today lives in Arlington. As far as these gentlemen remember, Yellow Cabs have always had orange doors, trunks and hoods, with black roofs and fenders.

"That's the color scheme that they were assigned by the taxi commission many, many years ago," said Vaughn Williams.

Maybe so -- Answer Man couldn't confirm this -- but why? There are yellow cabs in the District, even if they are not Yellow Cabs. Dial Cabs are bright yellow. Fairway Cabs are pale yellow.

Alexandria Yellow Cabs are, thankfully, yellow. But in the mid-1980s, the Arlington Yellow Cab company changed the color of its fleet from "a kind of bland yellow" to a "bold yellow," according to Charlie King, the company's president. What he calls bold yellow, someone else might call orange.

Before we get to why the District's Yellow Cabs aren't yellow, let's explain why nearly every American burg big enough for a stop sign has a Yellow Cab Co.

In 1907, Chicago used-car salesman John Hertz turned a surplus of customer trade-in vehicles into a taxi company. Legend has it that Hertz commissioned a study on which paint color would be most noticeable to potential customers. Yellow, his researchers reportedly told him.

Hertz quickly had success with his canary-colored fleet, ordering new cars to supplement his collection of repurposed used cars. But Hertz felt that the cars American manufacturers were making were not suitable as taxis. So in 1915 he founded the Yellow Cab Manufacturing Co. and began making specialty vehicles, starting with the 24-horsepower Model H.

Hertz became the Johnny Appleseed of the American taxicab business, selling his cabs -- along with instructions on how to operate the business -- to entrepreneurs across the country. As noted in "The Standard Catalog of American Cars: 1805-1942," "Yellow taxis were not always that color, the choice being up to the operator."

Aha! A clue. And it's a clue that dovetails with a 1927 reference in the New York Times that dates the founding of Washington's Yellow Cab Co. to about 1917, or about the time that Hertz started selling his custom vehicles.

(Hertz got out of the taxi business in the 1920s, when he bought a Chicago rental car company and renamed it Hertz Drive-Ur-Self System. He took the color yellow with him, and today that's still the color of Hertz's logo.)

Now Answer Man must speculate.

Let us suppose that Hertz's highly publicized success led cab companies across the country to ape his formula, right down to the yellow-painted vehicles. Let us assume that this happened in Washington. Let us assume that when a Hertz-approved Yellow Cab Co. arrived in Washington in 1917, there was already another cab company using the yellow color but not the Yellow name. The Yellow Cab Co.'s name would have indicated that it used Hertz-supplied vehicles, but it would have had to select another color scheme.

This is all conjecture, and Answer Man apologizes for not having an ironclad answer. What is clear is that cab companies have always taken their colors very seriously. In 1926, the Philadelphia Yellow Cab Co. valued the color -- just the color -- of its taxis at $1 million.

From the early days of the taxi industry, companies were suing one another over unlawful copying of a color. In 1984, Arlington's Red Top Cab Co. sued Washington's Mayflower Cab Co. because the D.C. firm had painted its cabs in a similar red-and-black pattern. "Let them not look for a free ride on the reputation of Red Top," said the Arlington cab company's attorney. Mayflower Cabs are now jade green metallic with black tops.

What Answer Man finds amusing is that when you're standing on a street corner looking for a cab, you usually don't choose one based on its hue. You just want the next one.

Today there are about 5,840 cabs registered in the District and 70-odd cab companies. Yellow Cab, with 650 cabs, has the most cabs flying under one banner.

The D.C. Taxicab Commission requires that new cab companies provide a paint chip of the color scheme they want for their fleet, said Kimberly Lewis, attorney adviser for the commission. Independent taxicabs -- those driven by an owner-operator -- must be painted either black or white.

Yellow Cab notwithstanding, there is some order to D.C.'s taxi livery: Silver Cabs are silver. Orange Cabs are orange. Diamond Cabs have diamonds painted on the side.

But guess how many stars there are on a Five Star Cab. That's right: none.

Julia Feldmeier researched this column. If you have a question, write answerman@washpost.com, or John Kelly, The Washington Post, 1150 15th St. NW, Washington, D.C. 20071.