[citation needed] Today's town and village of Green Island is connected to the mainland on the west side of the Hudson River.

[8] Much like its larger neighboring cities; Troy, Watervliet, and Cohoes; Green Island was a major manufacturing and transportation center.

In 1823, the Federal Dam was built between Green Island and Troy, allowing for year-round navigation north on the Hudson River to Waterford and Lansingburgh.

[8] The Rensselaer and Saratoga Railroad built its locomotive and car shops in 1842 in Green Island.

[13] It was automobile manufacturing, and not the railroads, that would soon become important to Green Island when Thomas Edison; whose General Electric was located in nearby Schenectady and who frequently fished off the northern end of Green Island; introduced his friend, Henry Ford, to the village.

Edison also considered building a factory at Green Island as well, which Ford believed would use electricity generated at his hydro power plant.

[18] Although the factory portion was demolished in 2004,[14] the dam remains active and continues to produce electricity, now owned by the Green Island Power Authority (GIPA).

The cheap electricity supplied by GIPA has lured many businesses to Green Island's north end, including Zak Incorporated, Honeywell Friction Materials, Long Island Pipe Supply, General Control Systems, Crystal IS, the New York State Department of Taxation and Finance, Sealy Mattress Company, Reliable Brothers, and Case Window & Door Inc.[18] The Rensselaer and Saratoga Railroad: Green Island Shops and St. Mark's Episcopal Church are listed on the National Register of Historic Places.

[20] He took over as head of the Green Island municipal Democratic Party in 1919, a position that he held until his death fifty years later in 1969.

[21] McNulty Jr. won his first election as town supervisor in 1949,[20] a position his son Michael would also hold.

Jack Jr., his son Michael and his daughter Ellen McNulty-Ryan have each served terms as Green Island's mayor.

GIPA was created in 1986 by the state and used eminent domain to seize the former Ford Plant hydroelectric dam in 2000,[22] from then-owner Niagara Mohawk.

[22] As of 2008, GIPA's rates are approximately 40% cheaper for the residents and businesses in Green Island than the traditional utilities in neighboring communities.