In the 1960s, a bank could refuse to issue a credit card to an unmarried woman; even if she was married, her husband was required to cosign. As recently as the 1970s, credit cards in many cases were issued with only a husband's signature. It was not until the Equal Credit Opportunity Act of 1974 that it became illegal to refuse a credit card to a woman based on her gender.

source

This Equal Credit Opportunity Act, passed a year after Roe v. Wade, is quite sickening because it has a two-fold effect: destroying the relationship between husbands and wives and enslaving more people to usurious loans.

These blanket statements about what banks (or other entities) could do in the past always bother me, especially when the statements are being used to show the supposed benefits of some national (and usually unconstitutional) national legislation.

As late as the 1960s, the majority of women were married and did not have employment outside the home.  Of course, a bank would refuse to issue credit to a woman in her own name without the authorization of the person who would earn the money which would repay any credit extended.  Furthermore, most economic transactions of that day were made by cash or check and not through credit.  

Leaving the question of usury aside, the fact is that even if a particular bank would not issue credit to a woman who had an income, a woman would likely have been able to obtain such credit (if she desired) from a competitor bank.  That provision of the Act was to solve a problem that really didn't exist.  Frankly, most legislation which requires or forbids private companies to operate in a particular manner are to solve problems that don't really exist--even if the issue involves some action that really does occur.

Widowed women must live off credit in order not to "die in poverty"?

Of course.  She probably aborted all her children.