An estimate for a national from the 1980s was about 20% of that. Adjusted for inflation, today that's still less than half that, about $400 million for a national change. So that's a little more that $1 per American, or about what we spend in Iraq every day, or less than 1% of the recent economic stimulus bill, etc. In short, on the scale of the US economy, it's not money. The cost argument has always been a tired joke, trotted out by metric opponents grasping at straws.
The reason for the the higher cost per km in AZ could be economies of scale, or other inefficiencies. It's not a good index for a national change. From: Stephen Mangum Sent: Monday, March 09, 2009 10:35 AM To: U.S. Metric Association Subject: [USMA:43595] Re: Arizona I-19 losing kilometer signs The Department of Transportation says that the Interstate Highway System is 46,876 miles [75,439 km] long. If the cost for changing over 100 km of roads is $1,500,000 then in theory to change over all Highway signs to metric would cost $1,131,585,000. Stephen Mangum On Sat, Mar 7, 2009 at 7:45 AM, John M. Steele <jmsteele9...@sbcglobal.net> wrote: This article http://www.gvnews.com/articles/2009/03/06/breaking_news/00mileposts0308.txt reports that Arizona Dept. of Transportation will spend $1.5 million of its Federal economic stimulus money to remove the metric distance signs along a 100 km stretch of I-19. This will include removal of the metric and rotation of already placed Customary signs to face traffic. Perhaps not quite the way we hoped stimulus money would aid metrication. (On the other hand, being a leader for 30 years, with no follower or plans for followers is proabaly silly too.) -- Stephen