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The primary strategy to reduce underage drinking, as well as drinking and driving, has been restricting access to alcohol via minimum purchase age laws. Since July 1988 the minimum legal drinking age has been 21 in all States. There is strong evidence that MLDA-21 laws reduce drinking, driving after drinking, and alcohol-related crashes and injuries among youth (McCartt, Hellinga, & Kirley, 2010; Shults et al., 2001; Wagenaar & Toomey, 2002). In fact, MLDA-21 laws reduced youth drinking and driving more than youth drinking alone (using the measurements of self-reporting and testing of impaired drivers in fatal crashes) (McCartt, Hellinga, & Kirley, 2010). Drinking and driving has become less socially acceptable among youth, and more youth have separated their drinking from their driving (Hedlund et al., 2001).

MLDA-21 law enforcement can take several forms:

  • Actions directed at alcohol vendors: compliance checks to verify that vendors will not sell to youth, dram shop liability laws, or responsible beverage service training laws.
  • Actions directed at youth: “use and lose” laws that confiscate the driver’s license of an underage drinker, “Cops in Shops” directed at underage alcohol purchasers, law enforcement “party patrols” using party dispersal techniques, and penalties for using false identification.
  • Actions directed at adults: beer keg registration laws, enforcement of laws prohibiting purchasing alcohol for youth, shoulder tap operations (in which decoy minors ask adults to purchase alcohol for them and if the adult complies, the adult is cited or arrested), and programs to penalize parents who provide alcohol to youth at parties.

Fell et al. (2016) found that nine laws that support enforcement of the MLDA-21 law significantly decreased fatal crash ratios of drinking to nondrinking drivers under 21. The laws are: (1) possession of alcohol, (2) purchase of alcohol, (3) use alcohol and lose your license, (4) zero-tolerance .02 BAC limit for underage, (5) age of bartender as 21 or older, (6) State responsible beverage service program, (7) fake identification support provisions for retailers, (8) dram shop liability, and (9) social host civil liability. The study estimated that combined, the nine MLDA-21 support laws save approximately 1,355 lives each year; however, only 5 States have enacted all nine laws. While these enforcement strategies have been used frequently, few have been evaluated.

The implementation of MLDA-21 laws for alcohol vendors, adults, and youth differs substantially from State to State. See the Alcohol Policy Information System for State-by-State summaries of some of the key provisions (APIS, 2021).


The minimum age to purchase alcohol is 21 years old in all 50 States and the District of Columbia.


Several reviews point to the effectiveness of MLDA-21 laws. Shults et al. (2001) identified 33 published studies examining the effects of changing the legal drinking age. Overall, changes to the MLDA affected alcohol-related crashes by 10% to 16%, with crashes decreasing when the MLDA was raised, and increasing when it was lowered. Wagenaar and Toomey (2002) reviewed 79 high-quality studies examining the relationship between the MLDA and crashes. Of these studies, 58% found fewer crashes associated with a higher MLDA, whereas none found fewer crashes associated with a lower MLDA. These findings prompted McCartt, Hellinga, and Kirley (2010) to conclude: “The highway safety benefits of MLDA-21 have been proven, and the cause-and-effect relationship between MLDA and highway crashes is clear. Deaths go up when the drinking age is lowered, and they go down when it is raised” (p. 180). NHTSA estimates that MLDA-21 laws have saved 31,959 lives since 1975 and an estimated 538 lives in 2017 alone (NCSA, 2019, 2022).


Costs may be associated with training needed for enforcement of MLDA-21 laws. (See Countermeasures on Zero Tolerance Law Enforcement and Alcohol Vender Compliance Checks.)

Time to implement:

MLDA-21 laws can be implemented as soon as appropriate legislation is enacted.

Other considerations:

  • Repealing MLDA-21 laws: From 2007 to 2010 six States introduced legislation allowing at least some people under 21 to purchase and consume certain types of alcoholic beverages (McCartt, Hellinga, & Kirley, 2010). None of these bills passed. There has been more research on the MLDA than perhaps any other alcohol-control policy (Wechsler & Nelson, 2010). Most traffic safety experts have concluded that MLDA-21 laws are effective, and they recommend strengthening enforcement of MLDA-21 laws and establishing policies to support them. For further discussion of this issue, see Wechsler and Nelson (2010) and McCartt, Hellinga, and Kirley (2010).
  • “Use and lose” laws: These laws allow confiscation of the driver’s license or postpone licensure for a period of time for youth who violate a State’s MLDA-21 law. Ulmer et al. (2001) investigated “use and lose” law implementation and effects in Pennsylvania. License suspensions for violations of MLDA-21 appeared to reduce subsequent traffic violations and crashes. In a national study, Fell et al. (2009) found “use and lose” laws were associated with a 5% decrease in fatal crashes among underage drivers. The study estimated that 165 lives would be saved each year if all States had these laws. “Use and lose” laws can be implemented quickly and inexpensively once enacted. To be effective, they should be publicized extensively. As of January 2021, there were 28 States and the District of Columbia that had mandatory “use and lose” laws and another 10 States had “use and lose” authority that may be applied in varying circumstances (APIS, 2021).
  • Keg registration laws: These laws link beer keg purchasers to an identification number on the keg, which provides a method of identifying adults who supply beer to parties attended by youth. As of 2021 there were 16 States that had mandatory keg registration laws (APIS, 2021), down from 30 in 2018. Utah only permits the sale of kegs to authorized beer retailers to dispense beer on draft for consumption on the beer retailer’s premises. In a study on the effectiveness of these laws, keg registration was shown to be associated with reduced traffic fatality rates in 97 U.S. communities (Cohen et al., 2001). However, the authors could not conclude that keg registration caused the lower fatality rates. A study by Fell et al. (2015) found that keg registration laws were associated with decreases in per-capita beer consumption but increases in the ratio of drinking to sober underage drivers involved in fatal crashes.
  • Social Host Liability: Under social host laws, adults who host underage drinking parties (specific laws), or who allow underage drinking to occur on their property (general laws), can be held accountable if a young person is subsequently involved in a crash. This liability might discourage adults (parents, older siblings, and friends) from purchasing alcohol for underage people or hosting an underage party. Conducting source investigations, in which law enforcement teams identify the providers of the alcohol, can be resource intensive and time consuming (Curtis & Ramirez, 2011). Moreover, the few research studies that have examined the effect of social host liability laws have obtained conflicting findings (Voas & Lacey, 2011). Nonetheless, comprehensive and well-publicized efforts to hold providers accountable appear to be promising. Social host laws, and their accompanying penalties, vary from State to State. A description of each State’s social host laws may be found in NHTSA’s Digest of Impaired Driving and Selected Beverage Control Laws (NHTSA, 2017). Another resource is available from the APIS (2021).
  • Underage Drinking Tip line: In 2006 Kansas launched a statewide underage drinking tip line: 866-MustB21 and Pennsylvania uses 1-888-UNDER21. The toll-free tip lines operate 24 hours a day, 7 days a week, for people to report parties involving underage drinking, plans to purchase alcohol for underage people, and willingness of retailers to sell alcohol to underage people. The effect of the tip lines has not been evaluated. Kansas pays about $200 a month for this service and no data on the number of calls, responses, etc., are available. Nebraska introduced a statewide underage drinking tip line in 2009, using the same phone number as Kansas. New York, Texas, and Iowa, have since implemented underage drinking tip lines.
  • Comprehensive community programs: Community programs focus on changing the local environment to prevent alcohol misuse through changes in ordinances and norms, incorporating discrete counseling and prevention programs, or combinations of such strategies (Fagan et al., 2011). Several comprehensive community initiatives have reduced youth drinking and alcohol-related problems (Fagan et al., 2011; Hingson et al., 2004; Shults et al., 2009). These initiatives typically bring together schools, health departments, and law enforcement, with alcohol sellers, parents, youth, and citizen organizations (Fagan et al., 2011). They may include school-based programs, law enforcement, media, and other intervention strategies. They require strong leadership and organization. They may take many months to plan and implement. Successful community initiatives are centered around data-driven practices and evidence-based measures, making the careful monitoring of program processes necessary to ensure quality outcomes. One example is a campaign conducted in Huntington, West Virginia, that included checkpoints to look for violations of the MLDA-21 law, checks of alcohol outlets to reduce sales to minors, and publicity for program activities. Roadside surveys conducted before and during the program showed a 93% drop in 16- to 20-year-old drivers having BACs greater than .05 g/dL (Insurance Institute for Highway Safety, 2008). Another promising program is Oregon’s Reducing Youth Access to Alcohol. The program involves community mobilization including “reward and reminder” visits (where vendors receive rewards if they decline to sell alcohol to a minor), regular compliance checks, enforcement of minor in possession laws, and media advocacy. The program was effective in reducing the sale of alcohol to minors: successful purchase attempts by minors dropped from 24% before the program to 5% afterwards. Additionally, the individual communities with the strongest programs also experienced reductions in underage drinking (Flewelling et al., 2013). For more examples of community programs, see: An Impact Evaluation of Underage Drinking Prevention Projects (Lacey et al., 2004).