There is consistent evidence that nighttime seat belt use is lower than daytime use. FARS data (Figure 1) shows this trend clearly. Observation data has also shown the difference. Observations in Connecticut (Chaudhary & Presser, 2006), Pennsylvania (Chaudhary et al., 2005), New Mexico (Solomon et al., 2007) and Indiana (Vivoda et al., 2006) all show that belt use was generally lower at night than during the day.