The National Automobile Dealers Association announced today that used-vehicle sales surpassed 4 million units across all retail channels for the month of May.

Although this year's May sales of roughly 4.02 million units passed last year's May sales of an even 4 million, this brought the year’s tally just past 14 million used cars and light trucks, putting 2015’s pace thus far just slightly behind 2014’s, where total used sales passed 14.1 million units by the end of May 2014.

“Private-party sales of used vehicles have declined this year,” said Steven Szakaly, NADA’s chief economist. “The cold winter combined with a wetter than usual spring dampened sales by individuals. New-car dealers, on the other hand, clearly benefitted from the increase consumer traffic during Memorial Day sales events that brought new car buyers in to shop for both new and used vehicles.”

To put that in perspective, new-vehicle dealers sold 1.52 million used units in May, a 3.6 percent increase year-over-year, while used-car dealers and private-party sales each declined 1.6 percent, respectively, compared to 2014.

Used-vehicle dealers sold 1.29 million vehicles in May; private parties sold 1.21 million units for the same month.