Did a PhD dissertation: "On the Algebra of Logic" at The Johns Hopkins University 1926 (1882) United States
Her dissertation was completed in 1882, however, the school did not award her with a Ph.D until 1926.
She waited 44 years to actually get her PhD, and died a mere 4 years later.
Source : Mathematics Genealogy Project http://genealogy.math.ndsu.nodak.edu/id.php?id=41944
Biography: Biography of Christine Ladd Franklin
Case study of the prejudices she suffered: Christine Ladd’s life story is a casebook study of the prejudices that women, who wished to enter academia suffered in the nineteenth and early twentieth centuries.