The majority of products found in an store in the United States are marked in dual units … English and metric.
Items made by very small local companies are usually labeled in English units only.
Wine and hard liquor is labeled in metric only. Most over-the-counter medicine is metric only, too.
Just eyeballing the shelves, about 10% of all items are marketed in “metric friendly” sizes, an example being two liter pop bottles. The “2 LITER” marking is dominant, with the odd English measurement downplayed. About 50% of health and beauty items use good, round metric measurements. The plastic bottle of Pantene shampoo by the tub is labeled “400 mL (13.5 fl oz)”. The box containing a bar of Basis soap is labeled “5.3 oz 150 g.”
In my laundry room, the Downy is labeled “1.8 L (60 fl oz).” The liquid Tide detergent, though, demonstrated excessive precision – “300 fl oz 8.87 L” something that I think is scaring a lot of folks here away from embracing metric units. There’s a belief that if the US goes completely metric, the stores will be stocked with oddball sized products for eternity – 454 gram packets of spaghetti and 355 milliter bottles of beer. Product packaging changes every few years for marketing purposes; so it’s no burden to alter packaging to avoid awkward sizes.
I think that sometime around 2010, the US will be more-or-less metric. Americans feel comfortable with metric units for volume, distance, and to some extent mass. Temperature … I think Americans will remain more comfortable with English units; if it’s 80 in Miami and 40 in Buffalo, the temperature difference is more apparent than if it’s 26 in Miami and 5 in Buffalo.
Construction and real estate will remain English for a long time … probably the rest of the century, given standardized building materials, previous land surveys and the English-based section-township-range system used in legal property descriptions. (When I was living in New Mexico, I frequently used surveys, some quite recent, with areas measured in cordels. *caballerias * and sitios, and distances measured in varas. Whether they were Southern New Mexico varas, Territorial varas, Pueblo varas, Texas varas, Arizona varas, California varas, Mexican varas or Castillian varas was anyone’s guess.)
Just like Brits measure their weight in stone, Americans will still state their weight using pounds.