According to marriage records in St Clair County, Joseph and Anna (Copeland) Phillips married in 1840 in St Clair County. However, when searching Ancestry for his Census entry (As the head of household), he’s noticeably gone. Chances are he’s living in St Clair County in 1840 and likely living on a family member’s land. So, we go to either William Phillips or Joseph Copeland in 1840.
2020 UPDATE: He’s living with his father in law Joseph Copeland! Joseph copeland has 5 kids – Anna, Freeman (1823 – ), Seely (1829 – ) Lucinda (1834 – ) and Ruthy (1841 – ), but he has 11 people living in the house. Joseph and his wife Charlotte are the oldest in the 30 – 40 male and female. There are 2 males between 20 and 30, but none of his boys would fit that age range. Anna would be 16 or 17 in 1840, which fits as well.