What part of the property would get a widow in the XIXth century in th USA?

Hello!
In the XIXth century in the USA, if a man died with no testament and left children (say, three sons) and a widow, what part of the property would get his widow? I have read somewhere once that she would get, without fail, a third or a half of all, and the rest would be divided among all his children, but now I can't find where I read it and can't remember what exact part it was.

Can anyone help please?
P.S. If it's important, I'm interested in 1830's or so...