The industry trade group said that equated to about 9.9 million barrels of oil and marked a 20.1 percent increase from the previous week.
The AAR said a cumulative 578,885 carloads, or 405 million barrels of oil, were delivered by rail as of Thursday, a 34.4 percent increase from the same time last year.
An accelerating pace of oil production in the United States has placed a burden on existing pipeline capacity, industry officials say. U.S. oil production has increased in part because of gains from states including Texas and North Dakota.
The AAR said its total for U.S. operations excludes deliveries from Canadian National Railway Co. and Canadian Pacific Railway.
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