I do not know her source (as there is no footnote) but Catherine Clinton has the number even higher than Jean Baker - over 80 trunks.
Article is here:
http://www.archives.nysed.gov/apt/magazi...nton.shtml
And, Becky Rutberg, in her book
Mary Lincoln's Dressmaker: Elizabeth Keckley's Remarkable Rise from Slave to White House Confidante, writes, "Lizzie helped the Lincolns' oldest son, Robert, pack sixty-four trunks and more than a hundred boxes in preparation for their move from the White House to Chicago, where Mrs. Lincoln decided to live." (from p.111)
Good luck with this one, Laurie!