There were no less than 30 “national emergencies” in effect as of February 1, according to a tabulation prepared by the Congressional Research Service. An additional 21 national emergencies that are no longer in effect were also identified by CRS.
Under the National Emergencies Act, a declaration of national emergency can be used to activate presidential powers that would otherwise be unavailable. President Trump has suggested that he could declare a national emergency in order to begin construction of a “wall” along the U.S. border with Mexico without congressional authorization.
See Declarations under the National Emergencies Act, Part 1: Declarations Currently in Effect, CRS Legal Sidebar, February 1, 2019, and Declarations under the National Emergencies Act, Part 2: Declarations No Longer in Effect, CRS Legal Sidebar, February 1, 2019.