The Association of American Railroads reported that while U.S. rail intermodal traffic in September was down 14.6 percent (to 993,235 units) compared with the same month last year, average weekly intermodal units in September 2009 were the highest since November 2008. In the monthly Rail Time Indicators report and video, AAR noted that the relative improvement in intermodal traffic may be related to retailers restocking shelves for the upcoming holiday season. The report, available at www.aar.org, comprises monthly rail traffic data framed with other key economic indicators to show how freight rail ties into the broader U.S. economy. September's monthly carload data showed a decline - down by 14.2 percent (at 1,380,684 carloads) compared with the same month in 2008. Weather may have played a role in this decline, with flooding in the Southeastern U.S. affecting traffic across many commodity categories. Lower natural gas prices and the relatively mild summer may also have been a factor in carload declines, since there was a drop in demand for coal - the single largest commodity shipped by railroads. Coal traffic was down 13.3 percent (to 645,843 carloads) compared with September 2008.