President's Day and Labor Day were associated with the highest 4-year average increases (12% each). Decreases in the 4-year average only occurred around two of the holidays, Independence Day ((7%) and Memorial Day ( (5%). Age groups 0Á4 and 5Á 17 had their largest 4-year average spikes around Labor Day (' 24% among 0Á4 and '30% among 5Á17), right after the beginning of classes as well as around President's Day (12% and 13%). The 18Á64 age group had its largest 4-year average increases during Christmas (19%) and Thanksgivings Days (15%). As for the 65' age group, Christmas (15%) and President's Day (14%) showed the largest increases. The span was much wider when analyzing year-specific holidays, from ' 40% after Martin Luther King Day in 2010 to (17% after Independence Day on the same year. Factors other than holidays could have also influenced the increases in ED visitors, such as the beginning of classes in August of each year and the H1N1 influenza epidemic in 2009. This research hinges on the comparison of the holiday period to a 28-day background. Future tracking of VDG should also be based on comparing the current holiday period to its mean of previous years to control for seasonal or day-specific effects. The availability of only 4 years of data prevented us from removing the seasonal effect in this research.