I made an informal survey of Thompsons from Butler PA in 1840 that have children in the 5 year old range. On the assumption that Levi Thompson would be about 5 or 6 and would still be living in the Butler area (lots of assumptions). If his age is right in his other census records he really should be in the 5 to 9 category. So I’ll give the amounts, and the total boys that should fit and then I’ll mark the ones who have 5-9 with a *.
Here is the list from the 1840 census of Butler PA:
james thompson from Cranberry two boys under 5 and two 5-9 (4 total) *
john thompson from Middlesex one boy 5-9 (1 total) *
john thompsoon buffalo one under 5 (1 total)
john thompson Donegal one under 5 and one 5-9 (2 total) *
2nd john thompson from Donegal one 5-9 (1 total) *
joseph thompson Cherry one under 5 and two 5-9 (3 total) *
moses thompson one under 5 (1 total)
robert thompson clearfield one under 5 (1 total)
robert thompson middlesex two under 5 and one 5-9 (3 total) *
robert thompson muddy creek one 5-9 (1 total) *
saml (samuel thompson centre butler two under 5 and three 5-9 (5 total) *
william thompson buffalo one 5-9 (1 total) *
william Thompson center three 5-9 (3 total) *
john thompson from Middlesex one boy 5-9 (1 total) *
john thompsoon buffalo one under 5 (1 total)
john thompson Donegal one under 5 and one 5-9 (2 total) *
2nd john thompson from Donegal one 5-9 (1 total) *
joseph thompson Cherry one under 5 and two 5-9 (3 total) *
moses thompson one under 5 (1 total)
robert thompson clearfield one under 5 (1 total)
robert thompson middlesex two under 5 and one 5-9 (3 total) *
robert thompson muddy creek one 5-9 (1 total) *
saml (samuel thompson centre butler two under 5 and three 5-9 (5 total) *
william thompson buffalo one 5-9 (1 total) *
william Thompson center three 5-9 (3 total) *
I guess the next step would be to try to identify these guys in 1850, what I always run into though is that I get confused with all the Johns and James and Williams and that people come and go quite a bit.