Purpose: The aim of this study was to estimate the prevalence of elevated blood pressure in adult patients with acute stroke in the United States (US). Methods: Patients with stroke were classified by initial systolic blood pressure (SBP) into 4 categories using demographic, clinical, and treatment data from the National Hospital Ambulatory Medical Care Survey, the largest study of use and provision of emergency department (ED) services in the United States. We also compared the age-, sex-, and ethnicity-adjusted rates of elevated blood pressure strata, comparable with stages 1 and 2 hypertension in the US population. Results: Of the 563 704 patients with stroke evaluated, initial SBP was below 140 mm Hg in 173 120 patients (31%), 140 to 184 mm Hg in 315 207 (56%), 185 to 219 mm Hg in 74 586 (13%), and 220 mm Hg or higher in 791 (0.1%). The mean time interval between presentation and evaluation was 40 ± 55, 33 ± 39, 25 ± 27, and 5 ± 1 minutes for increasing SBP strata (P = .009). A 3- and 8-fold higher rate of elevated blood pressure strata was observed in acute stroke than the existing rates of stages 1 and 2 hypertension in the US population. Labetalol and hydralazine were used in 6126 (1%) and 2262 (0.4%) patients, respectively. Thrombolytics were used in 1283 patients (0.4%), but only in those with SBP of 140 to 184 mm Hg. Conclusions: In a nationally representative large data set, elevated blood pressure was observed in over 60% of the patients presenting with stroke to the ED. Elevated blood pressure was associated with an earlier evaluation; however, the use of thrombolytics was restricted to patients with ischemic stroke with SBP below 185 mm Hg.