This is a little late but I just got on the internet a short while ago and just saw your message.
There was an Alfred Allen in Pike County, Illinois in 1850. He was located in Township 7 South Range 2 West 4th Principal Meridian.
He is shown with his wife Martha and a three year old girl named Martha.It shows him as being 45 years old and a farmer whose property was valued at $1000.00. He was born in KY.His wife was 41 years old and was born in PA.His daughter Martha was born in Illinois.
Hope this is some help.
I am looking for a Sintha Allen. I think her father's name was Thomas Allen.She married my gg Grandfather William Stanfield he was born in 1809 in KY.They were married sometime before 1828.William and his Father and a close neighbor named Thomas Allen bought land in Scott County, Illinois around 1830. Also William named one of his sons (My Great Grandfather) Thomas Allen Stanfield.