The penny press, which emerged in the United States during the 1830's, was a powerful agent of mass communication. These newspapers were little dailies, generally four pages in length, writ ten for the mass taste. They differed from the formal presentation of the conservative press, with its emphasis on political and literary topics. The new papers were brief and cheap, emphasizing sensational reports of police courts and juicy scandals as well as human interest stories. Twentiethcentury journalism was already foreshadowed in the penny press of the 1830's. The New York Sun, founded in 1833, was the first successful penny paper, and it was followed two years later by the New York Herald, published by James Gordon Bennett. Not long after, Ho race Greeley issued the New York Tribune, which was destined to become the most influential paper in America. Greeley gave space to the issues that deeply touched the American people before tile Civil Warabolitionism, temperance, free homesteads, Utopian cooperate settlements, and the problems of labor. The weekly edition of the Tribune, with I00,000 subscribers, had a remarkable influence in rural areas, especially in Western communities. Americans were reputed to be the most avid (热心的) readers of periodicals in the world. An English observer enviously calculated that, in 1829, the number of newspapers circulated in Great Britain was enough to reach only one out of every thirtysix inhabitants weekly Pennsylvania in that same year had a newspaper circulation which reached one out of every four inhabitants weekly. Statistics seemed to justify the common belief that Americans were devoted to periodicals. Newspapers in the United States increased from 1,200 in 1833 to 3,000 by the early 1860's, on the eve of the Civil War. This far exceeded the number and circulation of newspapers in Eng land and France. What is the author's main point in the first paragraph?