.
Three Perspectives on the Men in the Street: Texts of William Dean Howells's "The Midnight Platoon," Stephen Crane's "An Experiment in Misery," and Theodore Dreiser's "Curious Shifts of the Poor" from Sister Carrie.
Research Collections
The Sister
Carrie Website at the University of Pennsylvania contains the
text of the novel, facsimiles of the typescript, and essays on the work
by distinguished Dreiser scholars. The general page for the
DreiserWebSource at this site includes photographs and a short movie
(in color) of Dreiser at Iroki. It also includes essays
on and lists of books in Dreiser's library.
Dreiser
papers at the Indiana Historical Society
A Guide
to the Theodore Dreiser Collection at the University of Virginia
Dreiser Collection at Cornell
James
D. Mooney papers at Georgetown
The "Three
Cities" project contains multimedia essays on Chicago and New York
from 1870-1930; it uses Sister Carrie in several essay segments.
The Theodore
Dreiser segment of C-SPAN's American writers series aired on 20 and
24 August 2001.
Dreiser Online contains recent bibliographies (since 1990), genealogies, a chronology of works, a brief biographical sketch, and a Dreiser chronology.
On An American Tragedy
Grace Brown's Letters
(.pdf) 
Note: Unfortunately, as of 2016, the State of New York has removed the trial transcripts and other materials at the links below. I'm leaving the links up in case they are reinstated in the future. In the meantime, here's a good article about the trial linking its details to Dreiser's novel: http://www.nycourts.gov/history/programs-events/images2/Judicial-Notice-11.pdf. See also Craig Brandon's Murder in the Adirondacks.
The Historical Society of the Courts of the State of New York includes information on the real-life Chester Gillette (Clyde Griffith in the book) murder case that inspired An American Tragedy, including a webcast lecture on the case and trial transcripts. The first 450 pages or so of the transcript focus on selecting jurors, etc.; the statement of the case concerning Grace "Billy" Brown (the Roberta Alden figure) begins in Vol. 1, p. 481. These can be compared with Dreiser's treatment of the case in An American Tragedy.
- Chester's letters to Billy, Vol. 1, p. 567
- Billy's letters to Chester, Vol 1., p. 570
- Witness hearing a cry at the time of Grace Brown's murder, Vol. 2, p. 89
- Testimony about Chester's recollections of the crime, Vol. 2, pp. 150 and following
- Chester Gillette's testimony, Vol. 3; his account of what happened, p. 24; p. 35, claims that he did not strike Grace Brown
- Mr. Mills's (defense lawyer) claim that Grace Brown committed suicide, Vol. 3, p. 510
The site also includes page images of Dreiser's suit against Paramount concerning the 1931 film adaptation of the novel. [As of 9.6.17--this has also been removed.]
Sites
International
Theodore Dreiser Society (image courtesy of this site)
Student study guide on An American Tragedy.
Works Available Online
Link to plain text or .html versions and some page image versions of all Dreiser's works available online at the Online Books Page: http://onlinebooks.library.upenn.edu/webbin/book/lookupname?key=Dreiser%2c%20Theodore%2c%201871-1945
Sister
Carrie (1900) (Online books page at U Penn)
Sister
Carrie (1900) (HTML from the Crossroads site at the University
of Virginia)
The
Financier (1912; text from Project Gutenberg)
Jennie Gerhardt
(1911; text from Project Gutenberg Australia)
The
Titan (1914; Project Gutenberg)
Twelve Men (1919; biographical sketches and stories, Project Gutenberg)
"Whence
the Song" from The Color of a Great City (New York: Boni &
Liveright, 1923)
An American Tragedy (1925; text in Australia; NO US ACCESS)
If you've ever wondered just how bad Dora Thorne is (according
to Ames in Sister Carrie), it's available at
http://digital.library.upenn.edu/webbin/gutbook/lookup?num=2374