The CONTAINER Act authorizes border states adjacent to Canada or Mexico to temporarily place movable structures like shipping containers on federal lands to secure the international border without obtaining special permits. States would only need to notify the relevant federal agency 45 days in advance of their intended placement. These temporary structures can remain on federal land for up to one year initially, with the option to extend them in 90-day increments if U.S. Customs and Border Protection determines that operational control of the border has not yet been achieved. The bill applies to federal lands managed by agencies including the Bureau of Land Management, Forest Service, Fish and Wildlife Service, and National Park Service. The legislation provides a streamlined process for border states to deploy barriers on federal property without standard authorization requirements, though federal agencies retain final approval authority over extension requests.