[5] He discovered his love of photography in junior high school,[6] learning different techniques from older photographers in his neighborhood and teaching himself to develop photos.

Baltrop enlisted in the Navy in 1969[7] as a medic during the Vietnam War and continued taking photos, mainly of his friends in sexually provocative poses.

[6][2] After his time in the Navy, Baltrop worked odd jobs as a street vendor, a jewelry designer, a printer, and a cab driver.

[8][9] Because he wanted to spend more time taking photos at the Hudson River piers, he quit his job as a cab driver to become a self-employed mover.

[10] Baltrop captured the gay cruising spots and hookup culture that existed in New York City before the AIDS epidemic.

[2][13] In 2012, the artist's solo exhibition titled Perspectives 179— Alvin Baltrop: Dreams into Glass in the Contemporary Art Museum Houston included almost 100 gelatin silver prints that were shot between 1969 and 1980.

In Don't let them see you, published in his book called The Piers, Baltrop had positioned his camera inside a darkened area looking out at the shadowy foreground and a male figure looking down at another, who is crouched beneath him and performing a sexual act.

Fiona Anderson's Cruising the Dead River: David Wojnarowicz and New York's Ruined Waterfront (2019) includes extensive analysis of Baltrop's photography in and among the piers.