Tuesday after MLK Day

In our office the Tuesday after MLK Day is one of the busiest days of the year. DPS, flats, and parcels are all higher than normal when compared to other Tuesday's after a holiday. Shit, we've had a couple of years where this Tuesday was the highest volume day of the year, including any day during the holidays. I've been in this office for six years and it has always been this way for us. Are we an outlier or does anyone else have unusually heavy days after MLK day?