This photo was found at an antique store in upstate New York. I thought at first the surname was Crogan, but upon closer examination, it clearly says Cregan. The first name is spelled with only one L, which may be significant.
The matte bears the stamp "Spear & Boardman, corners of Rivers & Fulton Streets, Troy, NY."
This woman appears to be around 25 years of age, and my guess is that the photo was taken around 1892. If those assumptions are correct, then she was born near 1867.
It is also unknown if Cregan is a maiden name or a married name.
Census records show a couple of possibilities.
1880 Census - Town of Saratoga - there is a family named Cragan (which may or may not be a misspelling) which consists of mother Alice (born abt 1831), daughters Carrie (1861), Mary (1864) and Nellie (1866). There is also a son James (1859) who works as a common laborer. All three daughters work at the cotton mill. The mother was born in Ireland while all of the children were born in New York. There is no mention of a father in the household. (The town of Saratoga is about 29 miles north of Troy.)
In 1896, there is a Nellie L. Cregan mentioned in the Saratoga Springs City Directory. She lives at 489 Woodlawn Avenue and is employed as a domestic. Woodlawn is the "carriage house" lane directly behind North Broadway where the large homes of the wealthiest members of the community are located.
1900 Census - Albany, NY - The is a Nellie Creagan (born Apr 1874) living with her husband Dennis Creagan (Feb 1874) on North Ferry Street. Both are born in NY of Irish parents. Dennis works as a conductor. Nellie has no occupation listed. Albany is very close to the town of Troy, where this photo was taken.
I will continue to work on this, but I fully expect she is one of the three above possibilities.