Key Points Summary – Highway in Kilometers

• I-19 is the only U.S. highway using kilometer signs instead of miles
• Built in the 1970s, it was part of a nationwide metric pilot program
• The road connects Tucson with the U.S.–Mexico border
• Critics push for change, citing confusion and national pride
• Supporters say it reflects cross-border culture and trade
• New signage could cost taxpayers millions
• Arizona transportation officials are now considering conversion

I-19’s Kilometer Signs Could Soon Be History

Interstate 19, the only highway in kilometers in the U.S., is under fire. As nationalist rhetoric surges again, political forces want to erase this metric legacy.

The road, which links Tucson to the border city of Nogales, was designed as a test run for a broader switch to the metric system. That national experiment collapsed decades ago. Yet, I-19’s kilometer signs survived — until now.

Recently, Arizona officials launched a formal review to determine whether the metric signs should be replaced with miles.

A Forgotten Experiment Resurfaces

Back in the 1970s, federal leaders wanted to align the U.S. with international standards. So they rolled out metric pilots on roads like I-19.

Although that dream quickly faded, I-19 never changed back. The metric markers remained as a relic of a different direction in American transportation.

However, with political pressure mounting, many now argue it’s time to complete the transition back to miles.

Supporters Say It Still Serves a Purpose

Despite the criticism, many locals defend the use of kilometers.

Since the road connects directly to Mexico, using metric signs helps drivers from both sides navigate more easily. Additionally, some see it as a symbol of cooperation.

“It’s more than just numbers,” said one Tucson business owner. “It shows we’re part of something bigger than ourselves.”

Nationalists Want the Metric System Gone

Nevertheless, that symbolism doesn’t sit well with everyone.

Some Arizona lawmakers, especially those aligned with former President Trump’s “America First” agenda, insist that all U.S. roads should follow U.S. standards.

“We don’t need foreign measurements on American highway,” one legislator declared. “Let’s restore order — one sign at a time.”

Taxpayers Could Foot a Massive Bill

Although the issue may sound simple, the cost of converting the signs could reach several million dollars.

Arizona’s Department of Transportation said replacing every sign would require both planning and precision. Moreover, the change might take years to complete.

Critics argue that money could be better spent fixing potholes or improving safety infrastructure.

Confusion or Character? Locals Weigh In

As the debate grows louder, public opinion in southern Arizona remains divided.

Some drivers say the metric signs confuse tourists and truckers from other states. Others believe the unique signage gives the region charm and a story to tell.

Meanwhile, tourism boards worry that changing the signs could frustrate international visitors who rely on the metric system.

What Happens Next? Decision Looms

For now, the state has not committed to a timeline or plan of action.

Officials are gathering feedback from lawmakers, local businesses, drivers, and residents. Ultimately, they will decide whether I-19 keeps its kilometers — or joins the rest of the country in miles.

Until then, the fate of the only highway in kilometers in America remains uncertain.