Hit-and-run crashes, particularly during night­time hours, pro­vide an indi­rect meas­ure of the incidence of drinking and driving; it is well-known to law en­force­ment that many drivers flee the scene of a nighttime crash to con­ceal their al­cohol-impair­ment. Figure 2 presents the numbers of nighttime hit and run crashes (in the two states for which data are avail­able) during the six-month periods fol­low­ing the be­ginning of enforce­ment of the states’ conforming laws, compared to data from the same six-month periods in the previous year.8 The figure shows that the numbers of hit-and-run crashes declined in both states during the first six months after enforcement of their conform­ing laws began, com­pared to the same six-month periods one year earlier. Chi Square tests found the difference to be statistically significant for Maine, but not for South Dakota (p= 0.05).