The first president to say it was Richard Nixon, who dropped the phrase during an attempt at damage control for the burgeoning Watergate scandal on April 30, 1973."Tonight, I ask for your prayers to help me in everything I do throughout the days of my presidency," he said. "God bless America and God bless each and every one of you."
The phrase didn't catch on during the Gerald Ford and Jimmy Carter years, but Ronald Reagan's presidency definitively ushered in the era of "God bless America." Reagan used the line when accepting the Republican Party's presidential nomination in 1980, and made it his standard sign-off once in the White House. Since then, it's become a standard part of the language of the American presidency.