They date back to the Roman Empire, when they were made of stone. Now they’re made of metal and they’re painted green -- and they cost a lot of green, too.

Millions of federal dollars have been spent over the last decade to install mile markers – or, sometimes, even one-tenth-of-a-mile markers -- along America’s highways. Now some critics are pounding the pavement to say we’re wasting precious money on those markers in the 21st century, when technology has rendered them obsolete.

These days, the critics say, if you’re stranded on the road and uncertain of your whereabouts, all you really need is a cellphone.

“We have to get smarter about spending this money,” said Pete Sepp, executive vice president for the National Taxpayers Union, a non-profit group dedicated to decreasing taxes and the size of government. “Building mile markers might be useful under some circumstances, but then with the age of GPS and other technologies, it might not be the smartest use of money.”

"Mile markers make no sense in our connected world, where geo-location is built in to the communications systems,” said John Dvorak, a tech columnist and podcast host.

The Federal Communications Commission requires all cellphone carriers to have enhanced 911 technology, so emergency dispatchers can locate a caller through GPS or cellphone towers. A caller’s whereabouts can be identified within 50-300 meters, according to the FCC. Some exceptions are made based on technology in certain areas.

This innovation has some critics scratching their heads and asking, “Why are we still planting mile markers?”

Tomas Saenz, an engineer for the Texas Department of Transportation, said the centuries-old system should stay in place because computers systems can crash.

“If, for instance, satellites go down, what are we going to do? They’re a good backup plan,” he said.

Despite new technology, the North Carolina DOT doesn’t plan to change the way it installs mile markers.

“Federal standard is every mile. Not everyone owns a GPS and they’re not always accurate,” said Tammy Stewart, spokeswoman for the North Carolina DOT.

But mile markers really provide no immediate help for travelers who don’t have cellphones or can’t get a signal -- they still have to locate a landline to call for help. And placing all those signs doesn’t come cheap.

In 2009, the Massachusetts DOT installed approximately 6,180 markers every two-tenths of a mile. At $125 apiece, that came to $772,250 in federal funds. They also put approximately 1,545 mile markers along interstates and freeways, costing $150 each to make and install. The entire project cost $1,004,250, the DOT reported.

In Pennsylvania, markers are located every two-tenths of a mile and every one-tenth of a mile along high volume areas along interstates, according to state transportation officials.

“If we have a crash, a lot of times law enforcement officers will write down the mile marker in his crash report,” said Saenz.

In North Carolina, markers are posted every mile, or every one-tenth of a mile, depending on the municipality or requests from emergency response services. In Texas, markers are placed every mile along interstates.

Rep. Frank Guinta (R-NH), a member of the House Transportation and Infrastructure committee, opposes the excess markers.

“Every dollar must be stretched.” Guinta said in a statement to FoxNews.com. “Common sense tells you it’s more important to address essential needs than to have every one-tenth of a mile marked with a sign.”

Guinta, a former mayor of Manchester, N.H., is concerned about the future strain on local taxpayers, as maintaining and replacing signs typically becomes the responsibility of the state -- and its taxpayers.

The Oregon DOT spent $38,000 in state safety funds to add markers every half-mile on highways. In August, they added makers along state highway 217 and 30 miles of U.S. Highway 26.

Don Hamilton, spokesman for the Oregon DOT, said emergency services had been requesting the additional markers.

“When the only reference on a highway is a mile-long stretch of road, emergency vehicles can only guess at the best on-ramp and often don’t guess correctly,” he said.

Hamilton said in two years they would analyze the test project and determine whether the additional markers have been helpful.

Dvorak concluded they should stay in place, as they serve many purposes.

“They are also handy targets for the random shotgun blast in remote areas. I say keep them!"

So thanks, Romans – your invention is still very popular. Very pricey, too.

Patrick Manning is part of the Junior Reporter program at Fox News. Get more information on the program here.