How long must a couple reside/cohabitate together before being considered or defined as common law?

I presume that you are asking about common law marriage. Correct? What is the location that you are asking about? The laws will vary depending on the location.

For instance, I know that it used to be, just across the Mississippi river from me in Iowa, it used to be seven years of cohabitation before you could be considered married.

Very few states in the US allow for common law marriage, most states will reconise it for those that meet the requirements in the past when it was more accepted.

Normally now you are merely shacked up for a long time.


Also beyond just living together, there has to nromally be actions, where the couple appears to be husband and wife, joint bank accounts, and the such

It depends on the state and their laws.
For example Pa
The state no longer recognizes common law but the commonwealth does but it is many used for the purpose of setting up
Bank account, rent or mortgage, or utilities in both your names and the intent to marry.
Common law does not include work benefits and so forth.

FinAid | FinAid for Educators and FAAs | Common Law Marriages

Alabama recognizes Common Law marriage if you hold yourself to be married (For ex. Having bills in your name as Mr. and Mrs etc.). It is sometimes difficult to prove though and mostly moot unless there is a child involved as Alabama is not a community property state.

Where Common Law Marriage is not recognized it is because the state wants to charge you a fee to get a license.

Under God's law you do need a license.