Jennifer Viegas is a contributor for Discovery News.

Of the top five cities in the nation to be targeted for terrorists attacks, two belong to California. Here are the top five U.S. cities for terrorist attacks.

The study period was from 1970 to 2007.

#5 Los Angeles, California

Number of terrorist attacks: 54

#4 Washington, D.C.

Number of terrorist attacks: 59

#3 San Francisco, California

Number of terrorist attacks: 66

#2 Miami, Florida

Number of terrorist attacks: 70

#1 New York City, New York

Number of terrorist attacks: 284

Nearly three-fourths of these attacks took place in the 1970s, followed by less frequent, but often more deadly incidents including the 1993 and 9/11 World Trade Center attacks.

Businesses and government facilities are the most frequent targets – not only in New York City, but throughout the United States.

“While al-Qaeda has launched the deadliest attacks on New York City targets, almost 40 other identified groups engaged in terrorism in this city from 1970 to 2007, representing a range of different ideologies, backgrounds and goals, with changing actors over time,” the report says.

Puerto Rican separatists, the Jewish Defense League and an anti-Castro group were the most active in the 1970s, with their attacks tapering off through the 1980s.

The full report is available online: