Definition of "carter"

They were all two-horse wagons with sacks piled high above their sides and covered with tarpaulins. The wagon train had evidently only just moved out, and the carters had not yet taken their seats but were walking alongside.

1989, Aleksandr Solzhenitsyn, translated by H. T. Willetts, August 1914, Farrar, Straus and Giroux, page 95