I have DONEGAN ancestors who came from ireland and ended up in Washington, D.C. (not sure they were always there, may have connections to NE before going to DC). I found the following census item for a widowed Julia DONEGAN (so that is probably her married surname, her maiden surename is unknown)who was b. in D.C. i have no idea at this time whether she connects to my DONEGANs or not:

1900 Federal Census - Pennsylvania
City of Philadelphia, E.D. 384, Page 172A
Enumerated 05 Jun 1900 by John W. Dubbs.

Lines 26-30:
2253 Westerlon? St. (very faint writing in lefthand margin):
DONEGAN, Julia, Head, W, F, b. Dec 1848, 51, Widow, Mrd. 35 yrs., had 3 children & 1 living, she & mother b. D.C., father b. MD, reads/writes/speaks English, rents, house;
------- Martha L. Daughter, W, F, b. June 1866, 33, Widow, had 1 child & 1 living, b. PA, father b. MD, mother b. D.C., Operator Gents ????, reads/writes/speaks English;
Anpperle, -----, Boarder, W, M, b. Jun 1867, 32, Single, he & both parents b. PA, Driver, can read;
Clegg, Samuel, Boarder, W, M, b. Mar 1866, 34, Single, b. PA, both parents b. England, Laborer Dy, can read/write;
Smith, Edna M., G-daughter, W, F, b. Apr 1890, 10, Single, she & both parents b. PA, School.
===end census item.

So, perhaps Martha was prev. mrd. to SMITH?