A growing empirical literature on how to measure uncertainty has emerged following the 2007–2008 financial crisis. This paper first reviews the different methods measuring uncertainty. Second, applying a principal component analysis (PCA) that includes the various measures of uncertainty provided by the literature, a monthly global measure of uncertainty for the United States on the period 1990–2020 is developed. If the first factor computes a general level of uncertainty, the second factor provides a switch between two natures of uncertainty: macroeconomic and financial. Applying a new SVAR framework where the identification of uncertainty shocks relies on event constraints, we get a negative effect of US general uncertainty on industrial production.