April 6 (UPI) -- On this date in history:
In 1830, the Church of Jesus Christ of Latter-Day Saints, originally known as the Church of Christ, was founded between three groups of followers in Fayette, Manchester and Colesville, N.Y.
In 1851, Portland, Ore., was founded.
In 1896, the first modern Olympics formally opened in Athens, Greece. The Olympics had last been staged 1,500 years earlier.
In 1909, explorers Robert Peary and Matthew Henson reached the North Pole. It would be November of the same year before the National Geographic Society confirmed the accomplishment.
In 1917, the United States declared war on Germany, propelling America into World War I.
In 1938, DuPont researchers Roy Plunkett and Jack Rebok stumbled upon the chemical compound that was later marketed as Teflon.
In 1947, the first Tony Awards, honoring distinguished work in the theater, were presented in New York City.
In 1968, federal troops and National Guardsmen were deployed in Chicago, Washington and Detroit as rioting continued over the assassination of Martin Luther King Jr.
In 1973, American League baseball teams used a designated hitter for the first time. It hasn't always been a popular rule.
In 1994, the presidents of Rwanda and Burundi were among those killed when their plane was hit by rockets as it was landing in Kigali, Rwanda. The attack triggered fighting between the Hutu and Tutsi ethnic groups that left hundreds of thousands of people dead in what became known as the Rwandan Genocide.
In 2004, the University of Connecticut became the first school to win both the NCAA Division I men's and women's college basketball championships the same year. The UConn teams did it again in 2014.
In 2005, Prince Rainier III of Monaco, one of Europe's longest-reigning monarchs, died from multiple organ failure at the age of 81. He was succeeded by Prince Albert, one of three children of Rainier and his wife, movie star Grace Kelly, who died in a car crash in 1982.
In 2009, a 6.3-magnitude earthquake struck central Italy's Abruzzo region, killing 307 people and causing damage throughout the city of L'Aquila.
In 2019, for the first time, a tremor was detected on the surface of Mars by the InSight lander's SEIS seismometer. NASA described the phenomenon as a marsquake.