MATES is a smaller, more intimate tandem rally held locally in the Mid Atlantic region. It was originally started at the behest of some tandemists that did not want to make the trek to New England to attend the annual ETR, but wanted a regional rally. MATES stands for Mid-Atlantic Tandem EnthusiastS, and historically has been held from North Carolina north to New Jersey, with half the rallies in Virginia. It has also served to get some teams involved with organizing a tandem rally without taking on the responsibilities incumbent with the significantly larger Eastern Tandem Rally. MATES rallies usually run from 35 to 50 tandem teams, where the current ETR rally target is 125 teams.
A list of all the past MATES rallies can be seen here.