George and Emily appear in the 1920 census as living in Monongahela, Washington Co., PA. George was born in England and immigrated in 1862. Emily was born in PA.
They appear in the 1910 census as living in Rostover, Westmoreland Co., PA.
They appear in the 1900 census as living in Mount Pleasant, Westmoreland County under the spelling of Dasson. They were married 36 yrs. Living with them are 5 grandchildren.
In 1880 they were living in Tioga County, PA. Living with them was daughter Margaret 15, born in Nova Scotia, son George W. 10, born in PA, and adopted daughter May Ann 4, born in PA.
In 1870 they were again living in Tioga County under the spelling of Dason with children Margaret and George.
Some of these records you can look at for free at familysearch.org and Ancestry.com. For those you cannot see for free I suggest checking with your local libraries to see if they have Ancestry or Heritage Quest.
I suggest finding out when and where George and Emily died if you do not already know. Then I suggest getting their death certificates and obituaries.
It looks as if George immigrated to Canada first and had at least one child there. He then probably moved to Pennsylvania and married Emily.