Abstract: A slam catch that holds a side-load trailer gate or door in a closed position relative to the body of a trailer having a primary gate closure mechanism by which the trailer gate is fully secured in the closed position. The slam catch includes a catch hinge mounted on the body of the trailer, a latch mounted on the trailer gate, and a catch pivotally coupled to the catch hinge and configured to automatically engage the latch when the trailer gate is moved toward the closed position. The engagement of the catch with the latch holds the trailer gate in a closed position so that an operator can secure the primary gate closure mechanism without having to physically hold the gate closed.