To understand Common Law marriage you have to go back to the fall of Roman Empire in the West. Under the Roman Empire All Marriages had to be performed by a Official of the Roman Empire. This remained the situation when the Empire became Christian. The problem occurred when the Empire fell and no one was left to perform the Marriage Ceremony. This was resolved by having the Couple themselves exchange vows (mostly in front of their local Parish Church but that was NOT required). After the Exchange of Vows the Couple and their Families would enter the Church and have the Parish Priest Bless the Marriage. Note the Priest did NOT married the Couple (For that was a duty of the State Under Roman Law) but each family had records that this was a Valid marriage but their own customs (remember this is the days where the extended family was much more important than it is today, thus any marriage was more a merger of two families than two people agreeing to be married).
Anyway this situation survived till the Renaissance where various "reformers" wanted to change and return to "Roman Law". Attempts were made but failed for the above had become deep rooted into people's conception of how a valid marriage came to be. Reformers wanted a return to Roman law but knew that was impossible thus in the Council of Trent (1645), the Marriage law was changed but only marginally by requiring all marriages in Catholic Countries to be performed by a Catholic Priest. This satisfied the legalistic wing of the reformers for you were now having valid Roman Civil Law Ceremonies instead of a mere blessing and the change was NOT that huge that people would ignore it (Most Marriages had been Bless by the local Parish Priest BEFORE Trent and thus the big change was the move into the Church as opposed to the exchange of vows on the Steps of the Church).
Thus all Catholic Countries of 1565 (Including Spain and Mexico, conquered by Spain in 1519) followed the Rules of the Council of Trent. Protestant Countries were slower at adopting the rule, but most did so by 1600 (and was one of the "Reforms" most Protestant Reformers wanted for the Catholic Church). The big exception was England and Scotland. England did not abolish Common Law Marriage till Marriage Act of 1753 (and retained it for cases here a Ceremonial Marriage was impossible). The Marriage Act of 1753 did NOT apply to Scotland thus Common Law marriage is still valid in Scotland.
Given that the 13 Colonies were formed BEFORE the Marriage Act of 1753, that act was ruled NOT applicable to the 13 Colonies (after July 4th, 1776 the 13 original States). Since the Marriage Act was NOT applicable to the 13 Colonies, it was ruled NOT applicable to any State, even if formed after July 4th, 1776 UNLESS that States adopted the Marriage Act or abolished Common Law Marriage on its own.
Under the English Common Law, you had two types of Common Law Marriage, In Praesenti i.e. in the present, when two people of the opposite sex who are NOT married (or incompetent) announce to each other that they are Husband and wife. For example in the olden days when a Captain married a Couple on his ship, the captain was NOT marrying the couple but witnessing and documenting the exchange of vows that makes up this type of common law marriage between the couple.
The second type of Common law Marriage was "In Futureo" (Spelling?) i.e. In the future. That was a promise to marry in the future followed by Sexual Intercourse. When Richard III made himself King of England at the death of his Brother it was based on a Legal Opinion that his Brother's marriage was Invalid (and thus the brother's two sons illegitimate) do to his brother having had prior to his Marriage made a promise to marry another woman and then had sex with her (Thus forming a Valid Common Law "In Futureo" Marriage).
Now the big issue was HOW to prove one of the above happened. When both parities agreed (or you had documentation that they were married such as filling out joint Income tax forms) there is no dispute, but when one claims that such a marriage occurred and the other denies it (and they is NO documentation or the documentation is unclear) then the test is did the couple hold out each other as Husband and wife? If yes, then that was "Proof" that an exchange of vows had taken place.
While England had two forms of Common Law Marriages, most US States only recognized one, the "In Praesenti". It look from this stature that the Texas Legislature adopted the "In Praesenti" Common law marriage AND the test when they was no other documentation.
Notice, NO TIME LIMIT is mentioned in ANY of the above. Technically you can be married under the common law even if all you did was talked to the other party once (In the case of "In Praesenti" Common Law Marriage) or had sex with the other party just once (in the case of "In Futereo" Common Law Marriage).
Most states have abolished Common law Marriage (my Home State of Pennsylvania did so effective January 1st, 2005). While various reasons are often given for the abolishment, the main thrust seems to be property. For example if you are married you have a duty to take care of your spouse, but if you are merely living together no such duty exists. Common Law Marriages were mostly used by the dependent spouse (Generally the woman but can be the man) to get the other spouse to take care of her or his personal needs WHEN THAT SPOUSE NO LONGER WANTED TO DO SO.
While the above seems to be the main reason for abolishment of Common Law Marriage, in earlier years (i.e. pre-1900) the reason seems to be that people would marry someone their family did NOT want them to and take they money to their new spouse instead of the spouse the rest of the family wanted for the heir. Yes, people wanted to "protect" family wealth more than marriages. As one wag pointed out, if you have a good solid relationship a Common Law Marriage was as good as a Ceremonial Marriage, the only time it was worse is if your relatives wanted to steal your money from your widow or widower.
While the Common Law Marriages was often cited as the cause of denying a Widow her dowry rights at the death of her husband, the more common action was to Deny the Widow that she was her husband's widow on the ground she did NOT have a valid Marriage. Abolishment of Common Law Marriage made this easier (and thus easier to take her money from the widow). Since about 1900 this has become less common given that most people with money now have Wills.
http://en.wikipedia.org/wiki/Common-law_marriagehttp://www.oneplusone.org.uk/marriedornot/PDF/CommonLawMarriage.pdf#search='Common%20Law%20Marriage%20in%20Present'http://www.unmarried.org/common.html For a list of States with Common Law marriages:
STATE-BY-STATE REQUIREMENTS TO FORM A COMMON LAW MARRIAGE:*
Alabama: The requirements for a common-law marriage are: (1) capacity; (2) an agreement to be husband and wife; and (3) consummation of the marital relationship.
Colorado: A common-law marriage may be established by proving cohabitation and a reputation of being married.
Iowa: The requirements for a common-law marriage are: (1) intent and agreement to be married; (2) continuous cohabitation; and (3) public declarations that the parties are husband and wife.
Kansas: For a man and woman to form a common-law marriage, they must: (1) have the mental capacity to marry; (2) agree to be married at the present time; and (3) represent to the public that they are married.
Montana: The requirements for a common-law marriage are: (1) capacity to consent to the marriage; (2) an agreement to be married; (3) cohabitation; and (4) a reputation of being married.
Oklahoma: To establish a common-law marriage, a man and woman must (1) be competent; (2) agree to enter into a marriage relationship; and (3) cohabit.
Pennsylvania: A common-law marriage may be established if a man and woman exchange words that indicate that they intend to be married at the present time.
Rhode Island: The requirements for a common-law marriage are: (1) serious intent to be married and (2) conduct that leads to a reasonable belief in the community that the man and woman are married.
South Carolina: A common-law marriage is established if a man and woman intend for others to believe they are married.
Texas: A man and woman who want to establish a common-law marriage must sign a form provided by the county clerk. In addition, they must (1) agree to be married, (2) cohabit, and (3) represent to others that they are married.
Utah: For a common-law marriage, a man and woman must (1) be capable of giving consent and getting married; (2) cohabit; and (3) have a reputation of being husband and wife.
Washington, D.C.: The requirements for a common-law marriage are: (1) an express, present intent to D.C. be married and (2) cohabitation.