HOW PREPARED IS YOUR CITY?
A look at the preparedness of the country's 30 largest cities and their ability to respond to potential disasters and terrorist attacks.
Are we ready?
Every American is now vividly aware of the threat of terrorism. Recent events have shown how everyday things -- a flight on a major airline, the U.S. mail -- can be transformed into deadly weapons.
As the U.S. government and private industry struggle to close the security gaps at airports and devise ways to screen mail for biological organisms, concerns are rising about a range of other potential dangers
How prepared are local, state and federal agencies to deal with the possibility of a large-scale biological or nuclear attack? CNN Presents takes a closer look at this crucial question.
From drill to real
The U.S. government for years has conducted mock terrorist attacks to test the emergency prepardness of various agencies. Last year, an operation known as TopOff, shorthand for top officials, conducted mock attacks in three locations: a nuclear strike in Washington D.C., a chemical strike in New Hampshire and a biological assault in Colorado
The Federal Emergency Management Agency's operation center monitored the simultaneous exercises, which included people acting out the roles of emergency workers, victims and even reporters from a Virtual News Network that was covering the "attacks." The world has changed a great deal since these drills were staged. Preparing for the next attack is no longer about play-acting for an unlikely event but gearing up for an immediate matter of life and death. The focus has shifted from "what if" to "what next.
Nuclear nightmares
Many Americans believed that the end of the Cold War signaled the end of the threat of nuclear war. But evidence that terrorists are working on a nuclear track has whipped up a new wave of anxiety.
Many Americans believed that the end of the Cold War signaled the end of the threat of nuclear war. But evidence that terrorists are working on a nuclear track has whipped up a new wave of anxiety.
Many countries besides Russia and the United States have nuclear capability
Fear of food 
The U.S. Department of Agriculture has put the nation's farmers on notice, asking grain storage facilities and veterinarians to be alert to the possibility of bioterrorism. Many experts say that cautious food handling can minimize risks to crops. But protecting livestock from the rapid spread of disease presents a bigger challenge because animals are bred, reared and transported in close proximity.
A USDA study found that a foot-and-mouth disease outbreak could spread to as many as 25 states within five days. While experts say it would result in few human deaths, the economic impact would be devastating
Health and Human Services Secretary Tommy Thompson says it is vital to beef up inspections of food processing plants. Play
The specter of smallpox 
In the mid-1960s, the World Health Organization (WHO) hired Dr. D. A. Henderson to lead an ambitious campaign to rid the world of one of its most dreaded diseases -- smallpox. Highly contagious, smallpox also has a high fatality rate, claiming about one-third of its victims. It killed 300 million people in the 20th century.
The WHO campaign lasted for 11 years and the last known case of the disease occurred on October 26, 1977. But samples of the virus survived in WHO labs in the United States and the Soviet Union. The Soviets experimented with smallpox as a biological weapon, but it is not known what happened to all of the scientists involved or the virus samples after the end of the Cold War.
Dr. Henderson now heads the U.S. Office of Public Health Preparedness and is once again faced with the threat of smallpox. The government has made it a priority to stockpile 300 million smallpox vaccine does in the next year, up from the current supply of 15 million
Chemical weapons
On March 20, 1995, members of a doomsday religious cult released the powerful nerve agent Sarin into five Tokyo subway trains heading into the city's busiest station. Twelve people died, many hundreds became ill, and thousands more were terrorized.
Chemicals were introduced as military weapons decades ago and remain a threat, despite an international treaty banning their use. Bill Dee, who oversaw the development of chemical weapons for the U.S. Army until the 1990 treaty, says "secrets aren't kept that long" and all that is needed to develop chemical weapons is a competent chemist.
Using the Tokyo Sarin attack as an example, many U.S. experts are urging an investment in training for local hospitals and emergency personnel to respond to a chemical attack, as well as research into treatments
Old-fashioned bombs and bullets 
American cities and states have a new mission since September 11 -- figuring out ways to prevent terrorist attacks at everything from harbors to nuclear plants to shopping malls. Baltimore Mayor Martin O'Malley and Maryland anti-terrorism officer Donald Lumpkins are among those aggressively working to fortify on a local scale
Despite a national fixation on exotic weapons like anthrax and smallpox, many experts say that the most likely threat is a conventional attack with old-fashioned bombs and bullets. Gas pipelines and freight trains loaded with hazardous materials are among the potential targets.
When eight cars in a train hauling hazardous chemicals derailed in a city tunnel last summer, Baltimore was paralyzed by the ensuing fire. The tunnel fire was an accident and none of the train cars carrying chemicals were punctured. But the incident was a wake up call to the city to prepare for the need to prepare for the worst.