VAN BUREN, Ark.--(BUSINESS WIRE)--USA Truck, Inc. (NASDAQ: USAK), a leading capacity solutions provider headquartered in Van Buren, AR, today announced its financial results for the three and six months ended June 30, 2015. Operating revenue for the quarter ended June 30, 2015 decreased 12.9% to $133.6 million from $153.3 million for the prior-year period. Base revenue, which excludes fuel surcharges, decreased 6.2% to $117.2 million in the June 2015 quarter from $125.0 million in the June 2014