Good question. The science of reconstructing fire history in the eastern US is just beginning in earnest. By just beginning I mean over the last 20 years. Much of the work has been conducted in coniferous forests of the east, though there are some nice exceptions in the midwest. Many records are rather short in the most eastern portion of the eastern US [only about 120-180 yrs], a period that is dominated by burning by European settlers [they burned as much, if not more than first nation people/Indians]. I do not know this part of the literature as well as others, but some good places to look are here:
Google publications in Scholar Google for Richard Guyette and Michael Stambaugh of the Missouri Tree Ring Lab [here is a good intro vid of Mike http://vimeo.com/14515784
]. While they have made a massive collection across the eastern US, much of their earlier work is in the midwest - http://web.missouri.edu/~guyetter/pubs.html
. Henri Grissino-Mayer of the University of Tennessee and Charles Lafon of Texas A&M are doing some nice work in the Southern Appalachians. Here are two recent publications: http://web.utk.edu/~grissino/downloads/Flatley%20et%20al.%20Landscape%20Ecology.pdf
. The Minnesota Tree Ring lab, Kurt Kipfmueller and Scott St. George, will start cranking out work from the Boundary Waters and points north: https://sites.google.com/a/umn.edu/umndendro/
. A couple of nice papers have started to come out of the West Virginia Tree Ring lab led by Amy Hessl: http://www.geo.wvu.edu/~ahessl/publications.html
. The three species paper is nice: http://www.nrs.fs.fed.us/pubs/40520
. I am on a paper in preparation with Ryan McEwan looking at fire history since the late-1600s at Lilley Cornett Woods.
My favorite from the WVU group is a look at the causes of fire in the contemporary records collected by the state of West Virginia. From what I recall, it burns a bit more often and the fires are large when it is dry, despite the contemporary use of fire by locals: http://bellwether.metapress.com/content/n232602j6322j3m5/?p=a79f955e00384ea5a0a3f9f3887d284f&pi=2
. So, extrapolating that record to long-term drought history would suggest it has burned more in the past due to a more favorable climate for fire (but, that is just speculation by me).
One of my favorite papers on fire in the east was conducted in Vermont red pine. They got a nice long record of fire: http://home.mtholyoke.edu/courses/jbubier/pdf/Mann94QR42.PDF
. It shows a slowing of fire in recent decades, as does fire records from the northern range limit of red pine in Canada and thereabouts. These records come from areas where humans have less of an impact on fire. Click on the "Cited by" link for this paper: http://scholar.google.com/scholar?hl=en&q=fire+in+eastern+canada%2C+red+pine+northern+range+limit&btnG=&as_sdt=1%2C33&as_sdtp=
. I've seen scattered papers showing wetting in the north. Given what we know about fire and trends in moisture in eastern North America, it might not be too surprising that fires have become less common.
I apologize if I left off other major pieces of contemporary work in the east. I imagine I did. Bud Heinselman did a nice piece in the early 1970s: http://www.frc.state.mn.us/documents/council/landscape/NE%20Landscape/NE_Update_2011/Reich_FirePatterns_NEMN_2012-02-15.pdf