Southwick was originally inhabited by either the Matitacooke, Mayawaug or Woronoake tribes of Native Americans.
In the mid-17th century, Pioneering English explorers moving up the Connecticut River Valley, seeking fertile farmlands and game, discovered the area and settled Southwick. It became a farming community, defined as the Southern (South-) village (-wick) part of the town of Westfield, Massachusetts. Early on, it was nicknamed Poverty Plains because the land was thought to be infertile and its first residential home was built by Samuel Fowler and his wife Naomi Noble on College Highway (US Rts. 10 and 202), about a quarter mile north of the current town center.
In colonial times, church attendance was mandatory. The 800 Christian residents of Southwick in the 1760-70s were required to travel to Westfield to congregate. Only by establishing their own church community could they establish their own parish, as they desired. On November 7, 1770, Southwick was incorporated as a separate district of Westfield. The area of Southwick became somewhat smaller in 1770. The southernmost portion of Southwick joined Suffield, Connecticut, as the result of a simultaneous secession of citizens in that part of the village.
Ultimately, Southwick became a fully independent town in 1775. The town remained divided until 1793, when Massachusetts claimed the area (known as the "jog"). A border dispute continued until 1804, when the current boundary was established through a compromise between Connecticut and Massachusetts. As a result of this border resolution, Southwick is the southernmost town in western Massachusetts.
In the early 19th century, the Farmington Canal and Hampshire and Hampden Canal was built to link New Haven, Connecticut, to Northampton, Massachusetts, through Southwick. Irish immigrants came to the area to labor on this project. Developers spoke of Southwicks potential, calling it the "Port of the World". Farmers conflicted with the prospect that the canal would drain the Lakes. It was reported that citizens would kick in the banks to damage the canal. Traces of the canal can still be found in the Great Brook and Congamond Lakes area. Due to winter freezings, summer drought and wildlife impact (beaver dams ...etc.), the canal was phased out in favor of the railroad.
Completed in the late 1840s, the New York/New Haven Railroad (New Haven/Northampton) was built alongside the canal (more or less) as a revolutionary mode for travel to and through Southwick. With the railroad came the ice industry and the tourist resorts around the Congamond Lakes, (which were named 'Wenekeiamaug' by the previously existing Indian tribe). Several ornate hotels and dance halls were built as well as a small amusement park. During the Industrial era, summer vacationers and daytrippers would escape the hot and dirty cities connected by the Northeast Railroad Corridor from New York City, Albany, Boston, Worcester, Hartford and especially Springfield. There was a special stop near the Lakes where visitors would disembark to swim and/or pile into canopied pleasure boats.
During the 1st and 2nd World Wars, trains loaded with soldiers would also pass through town. It has been noted that local girls would gather letters thrown by the soldiers from the train - and forward them to the intended recipients at the Post Office. The last train to pass along these tracks was around 1976. As of 2008, the old rail way is in the process of being converted into a railtrail connecting to Granby, Connecticut.
All of Southwick's grand hotels and ornate train stations have since been torn down. Babbs Roller Skating Rink (on the Suffield, CT side of Congamond Lakes) is all that remains of the amusement park.