A yard is 0.9144 meters exactly. Feet, inches and miles are defined in terms of inches. A pound is defined as 0.45359237 kilograms exactly. Ounces, grains and all the rest fall from that. Gallons in the US are defined as 231 cubic inches, which means they're metric, too. Gallons in the UK are defined in terms of liters directly.
the US has been using the metric system since 1959. We just have a peculiar affinity for nostalgic conversion factors.