Humphrey, Carol Sue. (1996) The Press of the Young Republic, 1783-1833. The History of American Journalism, No. 2. Westport, CT: Greenwood Press.
Huntzicker, William. (1999) The Popular Press, 1833-1865. The History of American Journalism, No. 3. Westport, CT: Greenwood Press.
Two good, up-to-date surveys of American journalism in the years between the Revolution and the Civil War, part of Greenwood Press's History of American Journalism series.
Barnhurst, Kevin G., and John Nerone. (2001) The Form of News: A History. New York: Guilford Press.
Another useful survey of American journalism, this one focused especially on large scale and interrelated changes in newspaper format, business models, and the concept of news, rather than particular incidents or personalities.
Baldasty, Gerald J. (1992) The Commercialization of News in the Nineteenth Century. Madison: University of Wisconsin Press.
The best explanation of how the landscape of American journalism changed from 1800-1900, when mass market commercial papers emphasizing topical news eclipsed newspapers as focused more narrowly on political or financial news.
Tucher, Andie. (1994) Froth and Scum: Truth, Beauty, Goodness, and the Ax Murder in America's First Mass Medium. Chapel Hill, NC: University of North Carolina Press.
A fun and fascinating look at the evolution of metropolitan penny papers through the lens of two murder trials.