House Speaker Nancy Pelosi of California says a wall on the U.S.-Mexico border would be “immoral.” Instead, she favors something she calls a “technological wall.” Another top House Democrat, Rep. Jim Clyburn of South Carolina, calls it a “smart wall.”

Instead of building an actual physical barrier of steel, concrete, or some other material, Pelosi, Clyburn, and other Democrats advocate employing an array of high-tech devices — drones, infrared sensors, surveillance cameras, and more — to keep track of activity at the border without physical impediments to discourage illegal crossings.