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 12 September 1918, John Julius May registered for the World War I draft. Resident of 2500 S. Balto, Baltimore, Maryland.; age 43; born 7 July 1875; white; native born; head manager for Zastrow Machine Co. at Thames, Baltimore, Maryland; nearest relative Louise May of 2500 E. Balto, Balto, Md. Medium height, medium build, brown eyes, black hair. [National Archives, World War I Selective Service Draft Registration Cards.]

1930 U.S. Census, Baltimore City, Maryland
Ward 12, Enumeration District 4-571, Sheet 6A
Caroline Apartments, 108 University Parkway
May, John J., head, rents for $120, owns radio, male, white, 54, married, age first married 25, not in school, can read and write, born in Maryland, both parents born in Maryland, president of Cannery Machine Co., wage worker, employed, not a veteran
May, Anna R., wife, female, white, 35, married, age first married 29, not in school, can read and write, born in Virginia, both parents born in Virginia, speaks English, no occupation