Why does American Gallon differ from British Gallon?

Question

In litres, that is.

When Gallon is actually a unit of measurement, it should be same in litres, isn't it?

*United States liquid unit equal to 4 quarts or '3.785 litres'.

*British imperial capacity measure (liquid or dry) equal to 4 quarts or '4.545 litres'.

Answer 1

Why not?  Most weights and measures were made up as people needed them.  Eventually, some were standardized, but when this standardization took place, communication between countries and hemispheres was not exactly easy.  The metric system was devised late in the 18th century (1789-1799).  Other weights and measures were around hundreds of years earlier.  The inch, for example, dates back to the 11th century where it was defined as the length of 3 barleycorns placed side by side.

Answer 2

I think the US wanted to be as far from england as possible

Answer 3

As far as I remember from my academic knowledge, there are two standard of measurement prevailing all over the world. One is British and the other is American standard. That could be the reason for difference.