Currently available on 2 streaming services.

Niagara - watch online: stream, buy or rent

You are able to buy "Niagara" on Apple TV as download.

Cast

Marilyn Monroe
Rose Loomis
Joseph Cotten
George Loomis
Jean Peters
Polly Cutler
Max Showalter
Ray Cutler
Denis O'Dea
Inspector Starkey
Richard Allan
Patrick
Don Wilson
J.C. Kettering
Lurene Tuttle
Mrs. Kettering
Russell Collins
Mr. Qua
Will Wright
Boatman
Minerva Urecal
Mrs. McGrand
Harry Carey, Jr.
Taxi Driver
Henry Beckman
Motorcycle Cop (uncredited)
Bill Coontz
Young Man (uncredited)
Robert Ellis
Young Man (uncredited)
Neil Fitzgerald
Customs Officer (uncredited)
Gloria Gordon
Dancer (uncredited)
George Ives
Carillon Tower Guide (uncredited)
Arch Johnson
Taxi Driver (uncredited)
Lester Matthews
Doctor (uncredited)
Sean McClory
Sam (uncredited)
Patrick O'Moore
Detective (uncredited)
Tom Reynolds
Husband (uncredited)
Willard Sage
Motorcycle Cop (uncredited)
Bert Stevens
Doctor (uncredited)
Nina Varela
Wife at Bus Station
Gene Wesson
Guide (uncredited)