iTunes called Bing Crosby "the most popular and influential media star of the first half of the 20th century," "the undisputed best-selling artist until well into the rock era," and "the most popular radio star of all time." (Source)
With a name like Bing, it's no wonder.
Actually, Bing was a name he got based on his childhood nickname, Bingo. He was born Harry Lillis Crosby in Tacoma, Washington in 1903. Just imagine if he'd gotten famous under that awkward moniker.
Crosby came into his own as a star of radio in the late 1920s and early 1930s, first as a touring member of the Rhythm Boys and then as a solo act. He had solo hits in 1931, 1932, 1933, 1934, 1936 and 1937—but the peak of his career didn't even occur until World War II, when he also became a bona fide film star. Perhaps even more famously, he recorded "White Christmas," which was released on Christmas 1941 and remained a top hit all the way through 1942.
One of the most important elements of Bing's career and ultimate success as a performer was his versatility. He began with singing jazz and pop tunes, and eventually expanded out to everything from country and blues to show tunes. He was the definition of easy listening, and to a great extent, his familiar baritone still defines that broad, odd genre. His successful entrance into film acting only boosted his profile further.
Crosby has been praised as a sort of American "everyman," a dubious tag that nonetheless fits the character constructed in "Brother, Can You Spare a Dime?" Although many of those out of work during the Great Depression were also women, non-English speakers and people of color, the profile of the jobless, depressed white male war veteran was a perfect part for Crosby to play. His performance struck an incredible chord with broke Americans.
Crosby died in 1977 of a heart attack after continuing to make successful albums through the 1950s and 1960s. He has been so successful that "Brother, Can You Spare a Dime?" is not so much a signature song—he has "White Christmas" for that, among other classic tunes—as it is an example of the extent of Bing Crosby's influence.
Decades and dozens of cover versions in, when we hear about "Brother, Can You Spare a Dime?" it's still the Bing Crosby version we hear about.