A container according the present application includes a container auto-lock system. The container auto-lock system is integrated into the outboard apertures of the lower castings of a domestic sized container. The container auto-lock system includes a locking mechanism which is configured to recess when the container is lowered onto a surface lacking an acceptable receiving aperture. The locking mechanism is also configured to automatically lock when placed on top of a domestic sized container. The container auto-lock system is configured to be compatible with international sized container by allowing the inboard apertures on each lower casting to be available for attaching the domestic container on top of an international container with a conventional locking device.