The town is named after Israel Putnam, a hero of the American Revolution. The town was part of the Provincial Patent (1764) made to officer veterans of the French and Indian War while the region was in Charlotte County.

1609, July Samuel Champlain discovered and entered the northern end of the lake which honors him today, Lake Champlain. He and a party of Huron Indians paddled up the lake from Canada. Their encounter with the Iroquois occurred on the lake’s western shores after two days of swift paddling. Some historians place this encounter in the present Town of Putnam in Washington County, NY. A few weeks later in the same summer, Henry Hudson sailed his ship Halfmoon up the great river that now bears his name until he reached the impassable rapids, just north of Albany. The claims of these two explorers ignited the flames of hostility that would continue for the next 150 years, the skirmishes and all-out battles between the French and British and their Indian allies known as the French and Indian Wars.

Putnam –like the Town of Dresden has east and west borders that are Lake Champlain and Lake George.  On the Lake George side is Gull Bay Preserve, with 472 acres in the Town of Putnam, provides scenic vistas of Gull Bay and southern Lake George. The preserve includes part of Sucker Brook, which is considered one of the most important wetlands in the Lake George watershed and is home to a great blue heron rookery containing over 30 nests.

Geographic locations
•    Blairs Bay – A bay on Lake George at Glenburnie.
•    Charter Brook – A strean entering Lake Champlain in the north part of Putnam.
•    Gull Bay – A bay of Lake George south of Camp Adirondack.
•    Lamb Shanty Bay – A bay on Lake George in the south part of Putnam.
•    Mill Bay – A bay on Lake Champlain.
•    Mill Brook – A stream in the south part of the town that empties in Mill Bay.
•    Mud Pond – A lake in the southwest part of Putnam.
•    Record Hill – An elevation north of Glenburnie.
•    Skerrey Point – A projection into Lake George forming part of Gull Bay.
•    Smith Bay – A bay south of Skerrey Point.
•    South Mountain – An elevation north of Record Hill.