How does Taxi Driver portray loneliness and violence in New York City?

In Taxi Driver (1976), director Martin Scorsese portrays New York City as a decaying, corrupt environment that fuels the loneliness and paranoia of its protagonist, Travis Bickle.1

Travis, a Vietnam War veteran suffering from chronic insomnia, experiences profound alienation from society. He views the city as "filth" and "scum," a perspective reinforced by the film's production during a real-life heat wave and garbage strike, which visually emphasized the city's perceived moral and physical decline. His isolation is absolute; he admits that loneliness has followed him everywhere, leaving him no escape.123

This internal state manifests as escalating violence. Travis’s inability to connect with others—exemplified by his failed attempt to court a campaign aide—leads him to fixate on "saving" a young sex worker, Iris. His descent into vigilantism is marked by mental preparation, the acquisition of weapons, and a violent, bloody climax. Ultimately, the film presents his violence not as a heroic act, but as a disturbing symptom of his fractured psychological state, leaving his future and mental stability in doubt.23