The Metro League in its current form was established for the 1984 season when two former baseball leagues dissolved. That year, nine Northern League teams and four from the Lake Division joined to create a 13-team conference. The league's membership grew to as many as 19 teams for the 2001 and 2002 season but went back to 16 for 2010-13, with the league dropping to 15 teams for 2014 with Vergennes Union High School taking a one-year hiatus from varsity baseball. In its normal 16-team format, each school plays a 15-game Metro League slate, comprising nearly the entirety of their maximum 16-game regular-season schedule.
As far back as the 1940s, the Northern League was populated by such current schools as BFA-St. Albans and Burlington and, before the explosion of union high schools, defunct institutions in Highgate, Jericho, Richmond, Swanton and Underhill. By 1968, Northern League members were BFA-St. Albans, Burlington, Champlain Valley, Essex, Lake Region, Montpelier, North Country, Rice, South Burlington, Spaulding and Winooski. Burlington, Montpelier, Rice and Spaulding were league powerhouses during the 1960s and '70s.
The Metro League earned its name due to nine of its original 13 members being located in the greater Burlington area and Chittenden County, Vermont's most populated county. Original members included former Northern League teams BFA-St. Albans, Burlington, Champlain Valley, Essex, North Country, Rice, South Burlington, Spaulding and Winooski, and former Lake Division teams Colchester, Milton, Missisquoi and Mount Mansfield.
Over the years, expanded membership has affected the layout of the conference. Middlebury and St. Johnsbury joined in 1987 and 1988, respectively, while the admittance of Lamoille, Mount Abraham and Vergennes in 1995 caused a radical change to the landscape. As a result of expanding to 18 teams that spring, the league evenly divided its members among North and South divisions.
During the eight years of split divisions, from 1995 to 2002, BFA-St. Albans, Lamoille, Milton, Missisquoi, North Country, Spaulding and St. Johnsbury remained fixtures in the North, while Middlebury, Mount Abraham, South Burlington, Vergennes and Winooski played in the South. Meanwhile, Burlington, Champlain Valley, Colchester, Essex, Mount Mansfield and Rice each rotated between divisions at some point.
Harwood joined the ranks of Metro squads in 2001, becoming the 10th North Division team, before 2003 brought about another major shakeup with the departure of Lamoille, Vergennes and original member Winooski. Back down to 16 teams, the conference merged its North and South divisions that year. Harwood eventually dropped out after the 2007 season, with the league membership holding at 15 for 2008 and 2009 before the reentry of Vergennes for 2010.
The Orrie Jay Trophy, which was first awarded to the Northern League champion following the 1973 season, became the honor for the annual Metro League winner upon the conference's founding. The late Jay, who retired in 1972, coached at Burlington from the 1940s into the '70s. Once the league split into two divisions in 1995, the Jay trophy went to the North champion while the South winner received an award named after Jim Carter, Winooski's coach from 1981 to 2000. With the divisions merging in 2003, the league's winner continues to receive the Carter award.
The Metro is one of three leagues in the state overseen by the Northern Vermont Athletic Conference, joining the Capital and Mountain divisions.