The API said that, for June, gasoline demand declined 2.5 percent compared with the previous year. Most other fuel types declined as well, though jet fuel demand increased in June 0.7 percent compared with the previous year.
API Chief Economist John Felmy said the decline in demand is consistent with falling retail sales and contraction in the U.S. manufacturing sector.
"A weakening economy requires less fuel and this by most measures is a weakening economy," he said in a statement.
Existing homes sales also declined in June. Major U.S. stock indices declined Friday following a negative outlook voiced by Federal Reserve Chairman Ben Bernanke.
API added that U.S. refinery production was up for all major products except for gasoline. June inputs were up to nearly 15.8 million barrels per day, a yearly record. Exports of refined products increased by 17.8 percent for June, something the API attributed to weak U.S. demand.