It looks like you're using Internet Explorer 11 or older. This website works best with modern browsers such as the latest versions of Chrome, Firefox, Safari, and Edge. If you continue with this browser, you may see unexpected results.
For the combined rankings of the top 175 think tanks worldwide (U.S. and non-US), consult pages 65-71 of the 2019 Global Go To Think Tanks Index. Links to all organizations mentioned are available in the appropriate regional lists.