The austere president who presided over the Roaring Twenties and whose conservatism masked an innovative approach to national leadership

He was known as "Silent Cal." Buttoned up and tight-lipped, Calvin Coolidge seemed out of place as the leader of a nation plunging headlong into the modern era. His six years in office were a time of flappers, speakeasies, and a stock market boom, but his focus was on cutting taxes, balancing the federal budget, and promoting corporate productivity. "The chief business of the American people is business," he famously said.

But there is...