America hasn't use the Imperial system since the turn of the 20th century. So either you really are old or you've been using US Customary Units (ain't that a mouthful), which, while based on the Imperial System, is different.
When I was going through school we used Imperial measurments in shop class, chemistry and elsewhere... Metric measurments came into the education system after I was through it, so I guess it's just stuck with me. In common speech, I think the terms are nearly interchangable... If you switch out meters, kilometers and meters, for my examples, people will understand what's being said. Obviously in professional settings, metric measurments become more valuable, but in common speech... :shrug:
Looking back at my post, I could even add that where my first set of examples used three different words, a metric version only uses two (meters and kilometers). As such, I'd think it could be argued that where metric system benefits the scientific fields, it actually harms the cultural ones, by removing from common usage, some words.