Hoping to keep the New England colonies dependent on the British, King George III formally endorses the New England Restraining Act on March 30, 1775. The New England Restraining Act required New England colonies to trade exclusively with Great Britain as of July 1. An additional rule would come into effect on July 20, banning colonists from fishing in the North Atlantic.

U.S. Secretary of State William H. Seward signs a treaty with Russia for the purchase of Alaska for $7 million. Despite the bargain price of roughly two cents an acre, the Alaskan purchase was ridiculed in Congress and in the press as “Seward’s Folly,” “Seward’s icebox,” and President Andrew Johnson’s “polar bear garden.”

On March 30, 1939, Detective Comics No. 27 appears on the nation’s newsstands, introducing the world to a new superhero, the Batman. Dated May 1939, the comic book featured the caped crusader on its cover, swooping through the air on a rope, while holding a bad guy in a headlock. “Starting this issue,” the cover announced, “the amazing and unique adventures of the Batman!”

Henry Wallace, former vice president and Progressive Party presidential candidate, lashes out at the Cold War policies of President Harry S. Truman. Wallace and his supporters were among the few Americans who actively voiced criticisms of America’s Cold War mindset during the late-1940s and 1950s.

A bomb explodes in a car parked in front of the U.S. Embassy in Saigon, virtually destroying the building and killing 19 Vietnamese, two Americans, and one Filipino; 183 others were injured. Congress quickly appropriated $1 million to reconstruct the embassy. Although some U.S. military leaders advocated special retaliatory raids on North Vietnam, President Lyndon B. Johnson refused.

On March 30, 1974, the Ramones play their first New York City gig, launching a punk-rock revolution.

John Denver scores his first #1 song, “Sunshine On My Shoulders,” on March 30, 1974. He would go on to become one of the most popular singer-songwriters of the 1970s.

On March 30, 2009, President Barack Obama issues an ultimatum to struggling American automakers General Motors (GM) and Chrysler: In order to receive additional bailout loans from the government, he says, the companies need to make dramatic changes in the way they run their businesses. The president also announced a set of initiatives intended to assist the struggling U.S. auto industry and boost consumer confidence, including government backing of GM and Chrysler warranties, even if both automakers went out of business.