Oct. 18 (UPI) -- On this day in history:
In 1776, the border between Maryland and Pennsylvania was established. Dubbed the "Mason-Dixon" line, it became the unofficial boundary between North and South.
In 1867, the United States completed its purchase of Alaska for $7.2 million, taking possession of the territory from Russia. It would be 92 years before Alaska was admitted to the Union.
In 1898, the United States took control of Puerto Rico one year after Spain had granted self-rule to the Caribbean nation.
In 1922, the British Broadcasting Corp. was established.
In 1925, Grand Ole Opry opened in Nashville.
In 1959, the Soviet Union announced that Luna 3, an unmanned space vehicle, had taken the first pictures of the far side of the moon. In 1987, a former Mexican spy claimed his intelligence unit stole the Soviet satellite while it was on tour in Mexico in 1959, providing the United States with valuable intelligence.
In 1974, the jury in the Watergate cover-up trial heard a tape recording in which U.S. President Richard Nixon told aide John Dean to try to stop the Watergate burglary investigation before it implicated White House personnel.
In 1991, Israel and the Soviet Union agreed to renew full diplomatic relations for the first time since 1967.
In 2007, former Pakistani Prime Minister Benazir Bhutto returned home after eight years in exile to triumphant fanfare that gave way to panic when a suicide bomber killed more than 140 people in her convoy. She wasn't hurt in that attack but was assassinated on Dec. 27 of that year in Rawalpindi.
In 2011, Gilad Shalit, a 25-year-old Israeli soldier kidnapped by the militant Palestinian group Hamas in a high-profile incident, was freed after being held for more than five years. His release came in exchange for 1,000 Palestinians who had spent years in Israeli jails.
In 2012, the number of people to pass through the Channel Tunnel between Britain and France passed the 300 million mark. The 31-mile tunnel beneath the English Channel opened in 1994.
In 2013, tens of thousands of commuters were stranded in the San Francisco area by the second Bay Area Rapid Transit strike of the year. It lasted four days.