The AAR said 14,400 carloads of crude oil, or about 10 million barrels of oil, were delivered on the rail system during the week.
The trade group said that so far this year 606,892 carloads, or about 424 million barrels of oil, were delivered by rail, a 33.6 percent increase from the same period last year.
The Energy Information Administration, the statistical arm of the U.S. Energy Department, said domestic oil production averaged 7.7 million barrels per day last month.
The AAR said its total for U.S. operations excludes deliveries from Canadian National Railway Co. and Canadian Pacific Railway.
An accelerating pace of oil production in the United States has placed a burden on pipeline capacity, industry officials say. U.S. oil production has increased in part because of gains from states including Texas and North Dakota.