<p>This study addresses three inter-related questions. First, to what extent are rank and file Americans’ opinions toward major international organizations (IOs) reliable signals of their views? Compared to other countries, Americans have relatively little direct exposure to the actions of IOs, thus suggesting to some that Americans’ views are largely “non-attitudes” as opposed to true political opinions. Second, has American support for IOs declined? Although the United States (US) has been a traditional leader in efforts to build multilateral institutions, there is a fairly common belief among the public and some scholars that the backlash against globalization has included a decline in public support for IOs. Third, what accounts for change over time in individuals’ opinions of IOs? Using a nationally representative five-wave panel survey, we demonstrate that Americans have reliable views of IOs. However, their opinions do not readily distinguish between different IOs, thus reflecting reliance on heuristics rather than knowledge of individual IOs. Analyzing five waves of views on four different IOs–the United Nations, the North Atlantic Treaty Organization, the World Trade Organization, and the World Health Organization, we conclude that there has been a negligible decline in support, but increasing polarization by political party. This shift occurred in response to the onset of COVID19 in the US, an event that was blamed on China by Republicans. Finally, we provide experimental results confirming that the globalist versus anti-globalist divide was firmly entrenched in the two major political parties before COVID19. Without elite cues or information about specific IOs, conservative Americans still assumed that even fictitious IOs were more liberal than identically described national organizations.</p>