This study aims to characterize longitudinal blood pressure (BP) trajectories from childhood in black–white and sex groups and examine the association between childhood level–independent trajectories of BP and adult hypertension. The longitudinal cohort consisted of 2732 adults who had body mass index and BP measured 4 to 15 times from childhood (4–19 years) to adulthood (20–51 years). Model-estimated levels and linear slopes of BP and body mass index at childhood age points were calculated at 1-year intervals using the growth curve parameters and their first derivatives, respectively. Linear and nonlinear curve parameters differed significantly between race–sex groups; BP levels showed race and sex differences 15 years of age onward. Hypertensives had higher long-term BP levels than normotensives in race–sex groups. Although linear and nonlinear slope parameters of BP were race and sex specific, they differed consistently, significantly between hypertension and normotension groups. BP trajectories during young adulthood (20–35 years) were significantly greater in hypertensives than in normotensives; however, the trajectories during middle-aged adulthood (36–51 years) were significantly smaller in hypertensives than in normotensives. Level-independent linear slopes of systolic BP showed significantly negative associations (odds ratio=0.50≈0.76; P<0.001) during prepuberty period (4–11 years) but significantly positive associations (odd ratio=1.44≈2.80, P<0.001) during the puberty period (13–19 years) with adult hypertension, adjusting for covariates. These associations were consistent across race–sex groups. These observations indicate that adult hypertension originates in childhood, with different longitudinal BP trajectory profiles during young and middle-aged adulthood in black–white and sex groups. Puberty is a crucial period for the development of hypertension in later life.