Amtrak took over passenger service in May 1971; Union Station was added to the National Register of Historic Places the next month following a local effort.

[9][10] A two-story Greek Revival depot was built near the modern location in 1852 with the arrival of the New Haven and New London Railroad (NH&NL).

[10] The NYP&B-era station was highly unpopular; the Bureau was petitioned for a replacement not long after it was built, and local newspapers took up the issue in 1874 and 1875.

[10] After the previous depot was destroyed, the Central Vermont Railroad (which then leased the New London Northern) began making plans for a larger replacement station.

[12] Noted American architect Henry Hobson Richardson, known for his public buildings including several Boston and Albany Railroad depots, was hired by the Central Vermont in September 1885 to design the new station.

[7] Although different from his other stations, the 2+1⁄2-story structure features many of Richardson's characteristic motifs, including its multi-faceted roof, prominent arched entrance, and elegant brickwork.

The bricks are arranged in a mixture of Flemish bond and two different herringbone styles, broken by details around windows and doors, to create visual interest.

[2] A projecting central section tempers the roofline on the east and west facades, while the dormers shown a slight Asian influence common in his designs.

The rear bay window – the lone circular element save for the matching arched front doorway – served as the ticket booth.

[2] The ceiling and third floor are suspended from the roof trusses using an array of 2-inch (51 mm)-diameter iron rods, which allowed for a large two-story waiting room without interior columns.

[14] The platform canopy was notable for matching the broad curve of the tracks; it originally extended further south, with a raised "eyebrow" section over State Street.

[11] Around 1912, New London citizens successfully petitioned the Public Utilities Commission for the installation of a footbridge connecting the station to the ferry docks in order to improve pedestrian safety.

[18] In 1961, the New London Redevelopment Agency called for the station to be demolished to make room for a shopping mall or department store as an "urban renewal" project.

Under the National Historic Preservation Act of 1966, the addition to the NRHP prevented local authorities from using federal funds for demolition, although the law did not provide for enforcement or punishment.

Robert P. Turk, director of the Redevelopment Agency, wrote a letter accusing preservationists of dealing in "pure academic nonsense".

[24] Union Railroad Station Trust asked the Boston architectural firm Anderson Notter Associates to prepare a study of adding office and restaurant space.

Notter convinced Amtrak to agree to a 20-year lease for part of the station at $45,000 annually, thus giving the group a stronger negotiating point.

[19][20] Union Station Associates spend hundreds of thousands of dollars on a full renovation of the building for combined use by Amtrak and commercial tenants.

When an engineering firm moved into the "Crow's Nest" of the attic space in the late 1980s, the building was fully occupied for the first time since the heyday of the New Haven railroad.

In the late 1990s, the city offered to buy the station for use as a maritime museum detailing the history of the adjacent Thames River.

[31][32] Late that year or early in 2002, the 1899-built freight house on the east side of the tracks was torn down as part of redevelopment sponsored by the New London Development Corporation.

[30] In 2003, the city used eminent domain to take portions of the station property in order to build a footbridge from the Water Street parking garage to the ferry slips on the east side of the tracks.

The city only wished to pay for the small area taken up by the footprints, but O'Donnell wanted more compensation because the large footbridge would detract from the aesthetics of the historic station.

He abandoned renovations to the upper floors, and was forced to consider ending the leases with Amtrak and Greyhound and seek alternate tenants.

[37] Two weekday midday trips were added in May 2013, while weekend service began on June 1, 2013, after the application for additional bridge closings was approved by the state Department of Energy and Environmental Protection.

[4] In 2006, the Southeastern Connecticut Council of Governments (SCCOG) began a study of how to improve the Regional Intermodal Transportation Center (RITC), including Union Station.

[14] The study analyzed problems with the RITC – including poor pedestrian connections, minimal bus facilities, and a lack of food vendors – and considered but rejected a move to a Fort Trumbull site.

[47] On January 12, the Council released the station from the 1960s urban renewal plan as part of an agreement with O'Donnell and Timken to ease the sale process.

The southbound platform is adjacent to the station building, and its high-level section requires crossing only a lightly used spur of State Street.

Current service consists of two daily buses in each direction operating along the I-95 corridor, with transfers available to other routes in Boston, New Haven, and New York City.