ETR is both the acronym for the Eastern Tandem Rally, and the Eastern Tandem Rally organization. From 1974 to around 2001, this made perfect sense as the rally was the sole focus of the organization. In the early 2000’s, however, some folks got to thinking that the vision for the organization could be extended more broadly: encouraging the sport of tandem cycling in the Northeast and Mid-Atlantic regions. Around that time the ETR organization started to to help out by extending its insurance coverage to first the MATES and then the ETOR offroad rally. The long term stability of the organization started attracting other enthusiasts that sponsoring these additional rallies and were interested in seeing that the rallies continued.
Since the ETR rally strives to serve both regions, it has traditionally tried to alternate between the Mid-Atlantic and New England territories every year. That ideal is ultimately fated to the locales chosen by those who volunteer to organize the next rally, however. The ETR has been as far south as Williamsburg, Virgina, as far west as Dellroy, Ohio and as far north as Burlington, Vermont. ETR grew from 7 teams in its first year in Cape May, New Jersey to 262 teams at Gettysburg, Pennsylvania in 1999.
A list of all the past ETRs can be seen here.