Assign multiple values to enum elements

Hi I have this enum currently

[Serializable]
public enum Country
{
    US      = 1,
    Canada  = 2,
}

When I usually get the integer from the database I convert it to the enum using

(Country) Convert.ToInt32("1")

I now have 2 sub regions in US and Canada, 1 & 2 for US and 3&4 for canada. So when I do

(Country) Convert.ToInt32("1") or (Country) Convert.ToInt32("2") i should get the enum to be US. and for 3 & 4 Canada. How do i implement this?

[Serializable]
public enum Country
{
    US      = 1,2
    Canada  = 3,4
}

Something like this. This is probably not right but just to give you an Idea.