Bert.

Why should you convert to metric?
Well I guess one good reason is that the only legalised measurement of length in the US is the meter ( metre in the rest of the world )so that makes the metric system of length measurement the only official one for you blokes.
This was all done by an act of Congress in 1861. In 1893 the United States Office of Standard Weights and Measures was given approval ( not an act of Congress ) to derive the yard from the legal meter.
The United States prototype meters No's 27 & 21 were received from the International Bureau of Weights & Measures in 1889. Meter No. 27, sealed in a metal case, is preserved in a fire-proof vault at the US Bureau of Standards.

The Imperial system of measurement ( inches, gallons etc ) has never been "legalised" in the US. Technically you are all breaking the law. It might be a useful defence against a speeding fine though. The cop will have written down your speed in miles-per-hour. In court you can say he used a non-legal unit of measurement, geez, I shoulda been a lawyer.

JG/FME.