Racial and ethnic differences in blood pressure (BP), regardless of antihypertensive medication use, contribute to cardiovascular disease disparities. We analyzed systolic BP (SBP) data from US adults in the National Health and Nutrition Examination Survey from 1999 to 2002 through 2015 to 2018 (n=51 743) to determine if racial and ethnicity disparities have changed over time. Among US adults not taking antihypertensive medication, the mean age-adjusted SBP (95% CI), mm Hg, in 1999 to 2002 and 2015 to 2018 was 119.6 (118.7–120.5) and 119.4 (118.7–120.1) for non-Hispanic White adults, 124.7 (123.7–125.7) and 124.9 (123.8–125.9) for non-Hispanic Black adults and 120.4 (118.6–122.2) and 120.4 (119.7–121.2) for Hispanic adults. The mean multivariable-adjusted SBP was 4.1 mm Hg (2.7–5.4) higher in 1999 to 2002 and 3.8 mm Hg (2.6–5.0) higher in 2015 to 2018 among non-Hispanic Black adults compared with non-Hispanic White adults, while there was no evidence of a difference between Hispanic adults and non-Hispanic White adults in 1999 to 2002 (−0.2 mm Hg [95% CI, −1.9 to 1.5]) or 2015 to 2018 (−0.8 mm Hg [95% CI, −1.8 to 0.1]). Among US adults taking antihypertensive medication, the mean age-adjusted SBP (95% CI), mm Hg, in 1999 to 2002 and 2015 to 2018 was 129.6 (126.7–132.4) and 127.1 (125.6–128.6) for non-Hispanic White adults, 136.9 (133.8–140.0) and 135.3 (132.5–138.1) for non-Hispanic Black adults and 133.9 (128.0–139.7) and 131.8 (127.6–136.0) for Hispanic adults. After multivariable adjustment, in 1999 to 2002 and 2015 to 2018, mean SBP was 4.8 mm Hg (1.8–7.8) and 6.5 mm Hg (4.5–8.4) higher, respectively, among non-Hispanic Black adults versus White adults, and 2.4 mm Hg (−2.6 to 7.3) and 3.6 mm Hg (0.8 to 6.4) higher, respectively, among Hispanic adults versus non-Hispanic White adults. In the United States, non-Hispanic Black adults continue to have higher SBP levels compared with non-Hispanic White adults.