No longer peddling primitive space ads in penny papers, the advertising executive was now deftly marrying word and image across the spectrum of print media on behalf of burgeoning giants of manufacture and service, wielding the power of life and death over consumer products. As the 1920s closed, advertising had grown itself from a dubious activity and negligible industry into a major part of the economy. American companies went from spending an estimated $700 million in 1914 to almost $30 billion a year by 1929, then about 3 percent of gross domestic product. Advertising was now as big as many of the industries it served.

Tim Wu, The Attention Merchants, loc. 245