If the September 11, 2001, attacks never happened, Americans would be marking some later date as the anniversary of the most devastating terrorist strike on the homeland in modern history.
The high water mark of terrorist attacks against Americans remains the late 1980s. Fueled by Kremlin funding, most of the attacks came on foreign soil: Europe, the Middle East and Latin America. Congressional hearings on terrorism became as numerous as new Taylor Swift boyfriends are now.
When the Soviet Union collapsed and the checks stopped coming, transnational terrorism threats quickly trended down.