1880 U.S. Census, Baltimore City, Maryland:
2nd Ward, E.D. 21, written page 43, enumerated 12 June 1880
Dwelling No. 331, Family No. 462
282 Canton Avenue
Schneider, Ferdinand, 49, tinner, born in Bavaria
Schneider, Anna, 41, wife, keeping house, born in Bavaria
Schneider, Frederick, 19, son, plumber, born in Maryland
Schneider, Charles, 17, son, tinner app’r, born in Maryland
Schneider, Lizzie, 14, daughter, at home, born in Maryland
Schneider, Kate, 10, daughter, at school, born in Maryland
Schneider, Anna, 7, daughter, at school, born in Maryland
Schneider, Maria, 4, daughter, born in Maryland
Schneider, Mainie, 2, daughter, born in Maryland

On 22 March 1900, The Baltimore Sun reported that a marriage license had been issued for John J. May and Mary Schneider, applicant George R. Froehlich of 1744 Eastern avenue. [The Baltimore Sun, 22 March 1900, page 10.]

1900 U.S. Census, Baltimore City, Maryland
Ward 7, Enumeration District 90, Sheet 6A
1614 Baltimore Street, Dwelling 92, Family 120
May, Charles L., head, white, male, born August 1848, 51, married for 32 years, born in Germany, both parents born in Germany, year of immigration 1850, 49 years in the United States, naturalized citizen, can read and write, speaks English, rents house
May, Louis, wife, white, female, born September 1850, 49, married for 32 years, mother of 7 children of whom 4 are living, born in Maryland, both parents born in Germany
May, Edward, son, white, male, born April 1873, 27, single, born in Maryland, father born in Germany, mother born in Maryland, occupation bottler mfc, 0 months not employed, can read and write, speaks English
May, John, son, white, male, born July 1874, 25, married for 0 years, born in Maryland, father born in Germany, mother born in Maryland, occupation salesman, 0 months unemployed, can read and write, speaks English
May, Charley, son, white, male, born November 1879, 20, single, born in Maryland, father born in Germany, mother born in Maryland, occupation salesman, 0 months unemployed, can read and write, speaks English
May, Maggie, daughter, white, female, born January 1882, single, born in Maryland, father born in Germany, mother born in Maryland, can read and write, speaks English
May, Mary, daughter in law, white, female, born November 1875, 24, married for 0 years, born in Maryland, both parents born in Germany, can read and write, speaks English

1910 U.S. Census, Baltimore City, Maryland
Ward 7, Enumeration District 90, Sheet 34B
2600 Jefferson Street, Dwelling 718, Family 738
May, John, head, male, white, 34, married once for 10 years, born in Maryland, both parents born in Germany, speaks English, cashier at ice plant, wage worker, not at work week of April 13, 0 weeks unemployed in 1909, can read and write
May, Mary, wife, female, white, 34, married once for 10 years, born in Maryland, both parents born in Germany, speaks English, no occupation, can read and write

On 20 June 1910, a notice in Der Deutsche Correspondent stated:
Ableben. — Gestern schied Frau Mary May, geb. Schneider, von Nr. 2600, Jeffersontrasse, nach kurzer Krankheit im Alter von 35 Jahren aus dem Leben. Die Verstorbene, welche in Baltimore geboren wurde, hinterlässt neben ihrem Gatten, Hrn. John J. May, ihren Vater, Herrn Ferdinand Schneider, zwei Brüder, dei Herren Friederich und Charles Schneider un vier Schwesten, die Frauen Wm. F. Inglart, Chas. Thomas, John Behr u Wilmer Barnes. Die Arrangements für die Beerdigung sind noch nicht getroffen.
Death. - Yesterday retired female Mary May, née Schneider, of No. 2600 Jefferson Street, after a short illness at the age of 35 years of life. The deceased, who was born in Baltimore, is survived by her husband, Mr. John J. May, her father, Mr. Ferdinand Schneider, two brothers Friederich and Charles Schneider and four sisters Wm. F. Inglart, Chas. Thomas, John Behr and Wilmer Barnes. The arrangements for the funeral have not yet been made.
[Der Deutsche Correspondent, 20 June 1910, page 5.]

MAY.—On June 17, 1910, after a short illness, at her residence, No. 2600 Jefferson street, MARY MAY (nee Schneider), aged 35 years, beloved wife of John J. May.
Due notice of funeral will be given.
[The Baltimore Sun, 18 June 1910, page 6.]

MRS. MARY MAY.
Mrs. Mary May, wife of Mr. John J. May, died last night after a short illness at her home, 2600 Jefferson street. She was a native of Baltimore and is survived by her husband, her father, Mr. Ferdinand Schneider; two brothers and four sisters.
[The Baltimore Sun, 18 June 1910, page 10.]

MAY.—On June 17, 1910, MARY MAY (nee Schneider), aged 35 years, beloved wife of John J. May.
Funeral from her late residence, No. 2600 Jefferson street, this (Monday) afternoon, at 4 o’clock.
[The Baltimore Sun, 20 June 1910, page 6.[

Mary’s headstone states:
Mary,
Beloved wife of
John J. May
Born
Nov. 20, 1875
Died
June 17, 1910