Updated: Feb 3, 2019
Mae C. Mayo was a younger sister of Lydia (Mayo) Decker. She was born on July 27, 1880, in Greenfield, Pennsylvania. She married William Lafayette Lewis abt. 1897-1898 and they had five known sons: Gilbert O. Lewis, Russell A. Lewis, Duane Lewis, Earl Lewis, and Ernest Lewis.
In 1900, William and May Lewis were renting a home in Scranton, Pennsylvania, at 1211 Diamond Avenue.  William's birthdate was given as June 1872 and "May" was born July 1880. They had been married two years and reported having one child born, who was not living at the time. Unless the house numbers have changed, the empty lot shown here is the place where their home had been at the time. (Alternate link).
In 1910, when the census was taken, the family was living in Berlin, Wayne County, Pennsylvania. William was a farmer, age 37, and reported being born in New York. Mae was not employed, age 29, and reported having had three children, of whom two were still living at the time: Gilbert O. Lewis (age 4), and Russell A. Lewis (age 1 yrs 6 mos). Both boys were born in Pennsylvania. 
In 1920, the family was counted on the census in Lemon, Wyoming County, Pennsylvania. William was 47, May was 39, Gilbert was 14, Russell was 11, Duane was 9, Earl was 6 and Earnest was 2.  This appears to be around the time the family photo, shown below, was taken. (Photo courtesy of Jim Dickinson). The youngest boy appears to be about 5 years old, so the photo was probably taken around 1923.
In 1930, they were counted on the census in Dalton, Lackawanna County, Pennsylvania. William was working as a "Dairy Man" on a dairy farm. "May C. Lewis" was 49 and reportedly married William when she was 17 and he was 25. Four sons were in the home: Gilbert O. Lewis, age 24, nightwatcher at the dairy farm, Russell A. Lewis, age 21, milker at the dairy farm, Earl R. Lewis, age 16, and Ernest M. Lewis, age 12.
Mae died at the age of 57 on June 12, 1938, in Dalton, Lackawanna County, Pennsylvania.  She rests in Fairlawn Cemetery in Dalton. A photo of her gravestone can be found on Findagrave.  Her husband, William Lewis, lived until 1963, and was also buried at Fairlawn. 
In the next photograph, Mae is shown at right, with her mother, Lycenia (Strong) Mayo, brother, Alvin Mayo, and two sisters, Lydia (Mayo) Decker and Lucy P. (Mayo) Hunt.
Photos courtesy of James H. Dickinson, great-grandson of Lydia.
See the Decker page for more on these families.
"United States Census, 1900," database with images, FamilySearch (https://familysearch.org/ark:/61903/3:1:S3HT-D1Z7-HPN?cc=1325221&wc=9BQR-82X%3A1030550501%2C1035656301%2C1035696701 : 5 August 2014), Pennsylvania > Lackawanna > ED 50 District 2 Scranton city Ward 2 > image 17 of 33; citing NARA microfilm publication T623 (Washington, D.C.: National Archives and Records Administration, n.d.).
"United States Census, 1920," database with images, FamilySearch(https://familysearch.org/ark:/61903/1:1:M6TD-SLM : accessed 21 November 2017), Gilbert Lewis in household of W L Lewis, Lemon, Wyoming, Pennsylvania, United States; citing ED 130, sheet 3A, line 48, family 69, NARA microfilm publication T625 (Washington D.C.: National Archives and Records Administration, 1992), roll 1667; FHL microfilm 1,821,667.
"United States Census, 1910," database with images, FamilySearch(https://familysearch.org/ark:/61903/1:1:MGWG-4C9 : accessed 21 November 2017), William L Lewis, Berlin, Wayne, Pennsylvania, United States; citing enumeration district (ED) ED 90, sheet 1B, family 14, NARA microfilm publication T624 (Washington D.C.: National Archives and Records Administration, 1982), roll 1428; FHL microfilm 1,375,441.
"United States Census, 1930," database with images, FamilySearch(https://familysearch.org/ark:/61903/1:1:XH3K-638 : accessed 21 November 2017), William L Lewis, Dalton, Lackawanna, Pennsylvania, United States; citing enumeration district (ED) ED 123, sheet 5A, line 37, family 121, NARA microfilm publication T626 (Washington D.C.: National Archives and Records Administration, 2002), roll 2048; FHL microfilm 2,341,782.
Findagrave Memorial ID 5497130.
Findagrave Memorial ID 5497126.
Pennsylvania Death Indices, Mae C Lewis, at Dalton, age 35, June 12, 1938. #55619. (Click here for details on how to order death certificates from the State. Fortunately, a copy of Mae's death certificate can be found here.)