This Tuesday, Sept. 30, 2014 photo shows a sign on northbound Interstate 19, near Amado, Ariz., in the southern part of the state, that tells drivers they are kilometers away from their destination. Although other highways around the country have some metric signs, I-19 is the only continuous highway that is entirely in the metric system. The signs were installed nearly 40 years ago as part of pilot program that aimed to introduce the use of the metric system in the United States. (AP Photo/Astrid Galvan)
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