SOME NOTABLE EXAMPLES OF NATIONAL EMERGENCY DECLARATIONS:

■ In 1917, at the onset of America’s entry into World War I, President Woodrow Wilson declared an emergency related to shipping in an attempt to increase the country’s ability to transport food and raw materials by water.

■ In 1933, shortly after taking office during the Great Depression, President Franklin Roosevelt used an emergency declaration to close banks in an attempt to halt bank runs. The move gave Congress time to pass the Emergency Banking Act, which allowed banks to reopen once federal examiners decided they had enough money to operate.

■ In 1970, President Richard Nixon declared a national emergency to break a postal strike, using the National Guard to deliver the mail. Nixon’s invocation of emergency powers in this case drew the scrutiny of Congress.

■ In 1971, Nixon invoked his emergency powers again, this time to impose a 10 percent duty on imports. The surcharge on existing tariffs applied to consumer and manufactured goods. The Supreme Court later ruled that Nixon had exceeded his powers.

■ In 1993, President Bill Clinton declared that the proliferation of nuclear, biological and chemical weapons constituted a national emergency.

■ Two weeks after the 9/11 attacks, President George W. Bush declared a national emergency “blocking property and prohibiting transactions with persons who commit, threaten to commit, or support terrorism.”