The rhythmic thump-thump-thump reverberates throughout the noisy cavernous building like a heartbeat or the dance floor of a rockin' good club.
Several decades old, the warehouse-like structure in Huntsville is an exclusive club of sorts. More than 100 men, by invitation-only and wearing identical white outfits, tolerate the din five days a week. And the beat rarely changes.
What they turn out by the thousands daily is arguably the most common physical link some 20 million Texas vehicle owners have to their state prison system, the nation's second biggest.
"Everybody's got one," Tom Pierce, the warden at the Texas Department of Criminal Justice Wynne Unit, said. "And they all came from the Wynne Unit."
Mini-assembly lines, four of them, staffed by Wynne Unit inmates, each spit out 35 to 40 Texas license plates every minute.
Stockpiles now are growing with the new general license plate design for passenger cars and trucks picked by Texans in an online poll conducted last year by the Texas Department of Transportation. The new "Lone Star Texas" plates should start circulating in a few months.
About 1.6 million of the current passenger vehicle plate -- the one with the cowboy on the horse and the oil derrick and space shuttle -- were left as of the end of February. As fewer Texans buy new cars during the economic downturn, the supply of old plates lasted longer than expected.
"Our numbers have been all over the map," Kim Sue Lia Perkes, a transportation department spokeswoman, said. "Sometimes only 300,000 a month are moving out, which is half our usual number for passenger plates.
"We originally expected to have our inventory exhausted by now, but we based our assessment on past trends. What we were unable to anticipate was the recent economic downturn that adversely impacted vehicle sales."
Perkes refused to allow The Associated Press to photograph the new plates coming off the production line, saying she "wasn't really ready" to show off the finished product and that the department would "make a big announcement when it's ready." An image of the new plate is on the agency's Web site.
The big switch to the new license design began around the first of the year at the Wynne Unit plate plant, which has been producing plates since the mid 1970s, said Dudley Park, 46, the plant manager.
The new plate has a white Texas star in the upper left corner over sky blue background splashed with red, "TEXAS" in bold white letters outlined in blue along the top, "The Lone Star State" in white script superimposed over a mountain horizon at the bottom. In the center, there are seven black digits -- one more than on the current plate.
The extra digit is needed to account for the state's population growth and corresponding jump in the number of cars and trucks. Simply put, the state ran out of unique combinations of six-digit numbers and letters after more than 31 million pairs.
An image of a state-shaped Texas Flag serves as a hyphen splitting the seven digits -- three on the left, four on the right.
Besides the new design and extra digit, the most noticeable change is that the plate is completely flat, except for a raised edge that serves as a frame. The numbers and letters no longer are stamped.
Instead, a computer-generated digital image is transferred onto a roll of adhesive-backed reflective material that's affixed to a like-size strip of aluminum. The aluminum, unfurled from 2,500-pound rolls, is sliced into the plate-size rectangles that will wind up on everything from BMWs to VW Beetles throughout Texas.
St. Paul, Minn.-based 3M Co. supplied the technology that first was used in Texas a few years ago to make speciality license plates.
It's been extended to the general plate-making in what's hailed as a more environmentally friendly process. In the past, a machine stamped letters and numerals into the metal, and paint was then applied to the raised digits.
"Now, we don't have to do that," Park said.
It means solvents are no longer needed for paint cleanup. Neither are the huge ovens that baked the freshly painted plates at 350 degrees.
One thing that didn't change is the cut of the chopping machines, which also knock out four mounting holes and produce the incessant thump-thump-thump that vibrates through the building at the northern edge of Huntsville just east of Interstate 45.
Once they're finished, each plate is inspected for defects by a team of inmates. They slip pieces of waxed paper between those that pass muster, pack them in boxes and then it's "out the back door," said Park.
The transportation department has been registering vehicles for nearly a century, taking over the duties from Texas counties in 1917 when it was known as the Texas Highway Department. License plates were made by inmates at the Walls Unit, a few miles south of the Wynne Unit, beginning in the 1930s. Some 40 years later, the operation moved to what used to be called the Wynne State Farm, a former plantation that first housed disabled or sick prisoners in 1883. It now has about 2,300 inmates, 160 of them working at the plate plant.
That number should dwindle to about 110 once the phaseout of all the old stamping machinery is completed, Park said.
Like nearly all Texas inmates able to work and assigned to jobs, they work for free.
In years past, Texas prisoners made plates under contract for other states, as well as for some countries in Central America. Now all the plant's capacity is needed to keep up with the demand for Texas plates. It churns out some 9 million plates a year, including hundreds of specialty plates promoting military affiliations, pro sports teams and everything from Louisiana State University alumni to Texas smiles and "God Bless Texas."
And all for a fee upwards of $30 above the normal general plate assessment.
"They should have done this years ago," Tommy Lopez, 50, of Dallas, an inmate who's worked at the plant for about four years, said of the new "Lone Star" design.
He said he also likes his prison job, although he's looking forward to completing his term for a sexual assault conviction.
"I'm fixing to go home in 14 months," he said. "Every car I'll see with a license plate, I'll be thinking about this."