First, studies of racial/ethnic differences across the lifecourse are predominately comprised of large cross-sectional samples of adolescents (Bachman et al., 1991; Feigelman & Lee, 1995; Kandel, 1995; Kandel et al., 1976; Swendsen et al., 2012; Wallace & Bachman, 1991) or adults (Alvanzo et al., 2014; Dunlop et al., 2003; D. Herd, 1990; Wallace, 1999; Watt, 2008; Witbrodt et al., 2014). Longitudinal studies are largely community and convenience samples with limited variation in age ranges (Brown et al., 2005; Caetano & Kaskutas, 1995, 1996; Cooper et al., 2008; Finlay et al., 2012; Myers et al., 1995; Weaver et al., 2011), with notable exceptions (Chen & Jacobson, 2012; K. M. Harris et al., 2006; Pampel, 2008). These longitudinal samples suggest convergence in tobacco (White et al., 2004) and marijuana use (Finlay et al., 2012), but not for alcohol (Caetano & Kaskutas, 1995, 1996). Data from the National Longitudinal Study of Youth indicated convergence in rates of cigarette smoking over time between White and Black Americans followed into their mid-thirties (Pampel, 2008). Confirmation of these findings and expansion to examine possible gender differences is necessary to fully elucidate lifecourse patterns of substance use.
