GREEN VALLEY - Don Herk sees no problem with an interstate sign about 200 meters outside his Arizona Family Restaurant telling motorists that Continental Road is 2 kilometers south.

"The kilometers make it a little unique to this part of the country," he said as cars whizzed by on Interstate 19. "It's something that's become part of my life."

Carolyn Rose, a retiree who lunched at Herk's restaurant on a recent weekday, said visitors from her native Wisconsin find the interstate's metric signs fascinating.

"We like the uniqueness of it," she said.

Decades after efforts stalled to convert the U.S. to centimeters, liters and celsius, signs lining the interstate's 100-odd kilometers are reminders of those days. Built in the 1970s between Tucson and the border, I-19 was the Federal Highway Administration's testing ground for kilometer markings and remains the nation's only highway marked completely in metric.

Not everyone views the metric signs fondly, however. The Arizona Department of Transportation has proposed using $1.5 million in stimulus funds to replace the aging signs and, in the process, phase out kilometers.

But a backlash from residents and businesses along the interstate, especially those in Green Valley, has officials pumping the brakes. In June 2009, Gov. Jan Brewer put the project on hold while ADOT surveyed public opinion on the change, and a decision is expected later this month.

Herk said he and most of his customers consider the metric signs part of the area's culture.

"I think most everybody has gotten used to it," he said. "I've been driving up and down this highway for 33 years, and we've got it figured out."

In addition, his business advertises that it's off Exit 65, as in 65 kilometers. Changing to miles would cost him some money because the interstate's exit numbers would change, Herk said.

Jim DiGiacomo, executive director of the Green Valley Chamber of Commerce, said it's a tall order these days to force businesses to spend money changing advertising, letterhead and brochures. He'd rather see the state use the money elsewhere.

"They should leave the signs alone until the economy picks up again," DiGiacomo said.

Based on complaints from businesses and residents in this unincorporated area, the Green Valley Community Coordinating Council raised concerns with the Pima County Board of Supervisors, which appealed to the governor.

"These are down times right now economically," said Stan Riddle, the coordinating council's president. "Merchants are having enough trouble just trying to make ends meet."

Linda Ritter, an ADOT spokeswoman, said the signs have to be replaced because they don't meet federal standards for reflectivity. If the project isn't done now with stimulus money, she said, Arizona will have to do it in the next few years with money from the state budget.

"We need to get the wheels moving on this project," she said, adding that if the I-19 signs aren't going in by March the stimulus money will be used for a different project.

The agency recently completed the assessment of opinions and will announce its recommendation soon, Ritter said. The I-19 project would have to be pushed back if the decision is to keep kilometers because ADOT would have to design new signs, she said.

ADOT has proposed that if the signs do change to miles, a small kilometer marking would remain in the corner for two years so that businesses and residents can have time to adjust.

Sahuarita Mayor Lynne Skelton said changing the signs to miles would be a symbol of progress, bringing the area in line with the rest of the country.

"We didn't develop the town around kilometers," she said.

Skelton said switching to miles wouldn't as big a shock as some residents and businesses contend, noting that speed limit signs are in miles per hour and that I-19 already has mile markers that face the road rather than oncoming drivers.

"I've never heard anyone say they come down I-19 just to see the kilometers," she said. "First time drivers say, Wow, this is different' then go about their business."

But Jim Green, owner of the Inn at San Ignacio in Green Valley, said the kilometer signs make tourists want to know more about the area's history and other attributes.

"There's something about it that makes us unique," he said.

Bruce Pheneter, an architect and member of the Tubac Historical Society, said the signs have become part of the area's character.

"I think the metric system along I-19 is kind of a community identification," he said. "It's worked its way into the culture and people have been able to assimilate it."