[2] The area now known as the City of Rensselaer was settled by the Dutch in the 17th century, who called it t'Greyn Bos, which became Greenbush in English.

Rensselaer was an early center of the U.S. dye industry in the United States and home to the country's first aspirin factory.

The city became a railroad hub in the 19th century; in 2020, Albany-Rensselaer was the ninth-busiest Amtrak station in the country and the second-busiest in New York State.

New Netherland 1609 Province of New York 1667 New York State 1776 The natives of the area called it Petuquapoern and Juscum catick, and the Dutch claimed the land in 1609 based on Henry Hudson's exploration of the Hudson River on board the Dutch ship, Halve Maen.

Later the area was called "De Laet's Burg" in honor of one of the directors of the Dutch West India Co. Settlement occurred at least as early as 1628.

By 1642, there was a brewery and many farms, also a ferry was established by Hendrick Albertsen running from the mouth of Beaver Creek in Beverwyck (Albany) to the future Rensselaer.

[5][6] The hamlet of Greenbush was a tract of land about one square mile in size, and is that portion of the city between Partition and Mill Street.

In the 19th century, Rensselaer became the site of the Boston & Albany Railroad's (B&A) passenger depot, shops, freight houses, roundhouse, and coach yard.

[9] When the NY Central and the B&A merged in 1900 the island's activities became less important, though a new roundhouse and coach yard was built even as many buildings were demolished.

[9] In 1881, the Hudson Riverfront Art Park in Rensselaer was the site of the first recorded major league Grand Slam in baseball history.

[10] In 1882, the Hudson River Aniline and Color Works built their first plant in Rensselaer (building 61), however it burned 13 years later.

[11] It was acquired by the Bayer Corporation in 1903,[12] which then built one of the largest and most up-to-date factories of its time in the US and the Rensselaer plant became the American home for the production of brand-name Aspirin.

[14] According to a promotional brochure issued around 1993 by the BASF Corporation the Rensselaer plant was the largest North American dyestuffs production facility.

In 1932, next to the BASF plant, the Port of Albany-Rensselaer was built, mostly in neighboring Albany, but also with 35 acres (140,000 m2) in the southern part of Rensselaer.

Though the bridge was to continue east through Rensselaer, with the South Mall Arterial connecting with Interstate 90 at Exit 8, this extension never materialized.

[17] In January 2023, final approvals were issued to advance the Barnet Mills Apartments redevelopment at the former site of Hilton Center.

The project is an undertaking by BBL Construction to revitalize the property along the Hudson River that sits adjacent to the city boat launch and park.

The grant-funded trail will have multi-modal connections to the Livingston Avenue Bridge, which is a reconstruction project valued at over $400 million that has received state and federal funds.

The campus which houses students in Kindergarten through 12th grade is the former location of Van Rensselaer Elementary school.

As of 2020[update] it was Amtrak's ninth-busiest station, as well as the busiest to serve a metro area with a population smaller than 2 million–[22] a distinction it has held since at least 2010.

The eastbound Lake Shore Limited reverses the process at Albany-Rensselaer and splits into two trains for onward travel.

Although not technically located within the bounds of the city, the New York Independent System Operator's (NYISO) headquarters shares the same zip code.

(now operating as Empire Generating Co, LLC) was granted a Certificate of Environmental Compatibility and Public Need for a 505-megawatt (MW) combined cycle cogeneration plant in 2004.

After additional filings, the project became a 670-MW (nameplate) combined cycle natural gas powered plant that went into service in September 2010.

It is located on an 88-acre former industrial area that was owned by BASF Corporation between Riverside Avenue and the Hudson River on the west, and the Port Access Highway on the east and south.

[34] In its 2018-2019 adopted budget, the City of Rensselaer notes a revenue of about $1.1 million from payments in lieu of taxes most of which can be assumed to come from Empire Genering LLC.