The partial federal shutdown lasted 35 days (Dec. 22, 2018 to Jan. 25, 2019), the longest in U.S. history. About 800,000 federal workers were affected (roughly 380,000 furloughed and 420,000 working without pay). The Congressional Budget Office estimated an $11 billion hit to GDP, with $3 billion permanently lost.
The standoff centered on Trump's demand for border wall funding and ended with a three-week funding bill without wall funds after mounting pressure, including air traffic staffing shortages and delays.