There might not be any new refineries, but capacity in the US has been increasing.
According to the annual BP review of world energy, in 1994 refinery capacity stood at 15,434,000 barrels a day, by 2004 it was up to 17,042,000 barrels a day.
Consumption has also increased, from 17,719,000 to 20,033,000 barrels a day.
In the same time, production in the US has gone down from 8,389,000 to 7,241,000 barrels a day.
So refinery capacity is roughly keeping up with demand for oil in the US, and over the last 10 years refinery capacity has gone from 1.84 times production to 2.35 times production.
World excess refinery capacity actually increased very slightly between 1994 and 2002, but has since halved, due to a sudden rise in production in 2003/04 (and has probably got worse this year)