Target: Houston

By 1955, the Cold War was on, and both the United States and the USSR were developing hydrogen bombs.

Houston, a city of nearly 600,000 at the time, underwent preparations in case Soviet bombers decided to drop nuclear weapons on the Bayou City.

In March of that year, the city's Civil Defense department released an evacuation map that Houstonians were urged to follow in an impending H-bomb attack. Considering the Gulf Freeway was the only freeway constructed at the time, residents likely would have faced a tough time getting out of town.

Katy Road, Hempstead Highway, Hardy Road, Mykawa, Almeda and Market were some of the roads identified as evacuation routes. All of the routes were to be one-way, outbound.

"If evacuation is ordered during daylight hours many families will undoubtedly be temporarily separated," the Houston Post wrote.

Here was a rough protocol of what to do, as published in the March 20, 1955, edition of the Post, with help from the city's Civil Defense department:

* A steady, five-minute blast from the city's air raid warning siren was a sign for every resident to tune their radio to 640 or 1240 AM. These were the CONELRAD frequencies that were allowed to operate once the alarm sounded. All other television and radio stations had to stop broadcasting. The order to commence evacuation would have been given over those two frequencies.

(CONELRAD stood for Control of Electromagnetic Radiation. Its purpose was to keep Soviet bombers from being able to home in on specific radio or television stations. By restricting broadcasts to two frequencies, it would potentially be difficult for the Soviets to single out a specific target to attack.)

* The other air raid signal (the one you never hoped to hear) was a warbling sound -- with the tone rising and falling repeatedly.

"This means that evacuation is out of the question. Enemy attack is imminent. You should take cover immediately," the Post wrote.

Motorists had to follow these tips when leaving the city:

* Pick up any persons needing transportation while stopped. Do not pick up pedestrians while your lane of traffic is moving.

* Should your car stall, it must be pushed off the road immediately and abandoned.

By the early 1960s, the chances of enemy bombers dropping bombs within the continental United States seemed pretty remote. ICBM's equipped with high-tech guidance systems posed a bigger threat. The CONELRAD system became the EBS (now EAS) system by 1963.

Freeways rendered this plan obsolete, but we know how effective freeways can be in an evacuation.

Nevertheless, here is the city's current evacuation plan.

The Federation of American Scientists produced a scenario detailing the effects of a nuclear weapon on major cities, including Houston.

More information on CONELRAD can be found here.