[1] Rossi was born in Volcano, Amador County, California, and came to San Francisco in 1890 with his widowed mother and six siblings after the family home and general store burned to the ground in minutes.

(Rossi's father, also named Angelo, left Italy in 1849 at age 16 aboard a ship loaded with marble that departed from Genoa.

When young Angelo arrived in San Francisco with his family, he attended school but left after sixth grade to work in jobs ranging from cash boy to clerk in a couple of different florist shops, including Carbone and Sons and Pelicano and Sons, which became Pelicano and Rossi when he became a partner in the early 1900s.

On July 19, 1934, Mayor Rossi spoke on national radio, "I congratulate the real leaders of organized labor on their decision and the part they have played in ending the general strike.

San Francisco has stamped out without bargain or compromise an attempt to import into its life the very real danger of revolt... We will deal effectively with the small group who opposed peace and plotted revolution."

In May 1942, six months after the bombing of Pearl Harbor, at the Tenney Committee hearings held in San Francisco, Rossi was subpoenaed, having been accused of supporting Italian fascism.

According to The New York Times of May 26, 1942, "With tears in his eyes and a voice that broke with emotion, Mayor Angelo J. Rossi protested today his '100 per cent' loyalty to America and told a committee of the California Assembly that his presence before it as a witness was 'based on the damnable lies of irresponsible people'."