Acceptable or not now a days?

I sincerely doubt that there are any 'pure' bred humans on this planet today. Homo sapiens sapiens has been around some 125.000 years and spread out from Africa. I'm guessing that means that Adam and Eve were actually Negroes, then? Anyway, dismissing all that religious tripe, if the first Homo sapiens sapiens came from Africa then it's the whites that are the mutations, right?

Of course it should be acceptable/legal.

Anyone should have the right to love/marry any other consenting adult in a situation that does not potentially cause harm.

The racists on here will argue that it "harms" the race or whatever. As if humans have not been intermingling within races forever. It is not something that causes harm. You have the right to choose not to do it yourself, but to maltreat others for their choices is wrong. It has nothing to do with you, it's all about the couple themselves.

I don't like the way the question is presented.

"I mean the marriage of two very different ethnic backgrounds, such as a black person marrying a white person"

Very different suggests that a white and black person are more different than another ethnic combination may be, and I reject that concept. We are all genetically of the human race, the difference is level of pigment.

But because you are talking about the 70's, I completely get where you are coming from. That is just a short time removed from a period in the United States where is was illegal for a black person and a white person to marry in many states, but Lucy and Ricky, a white woman and a Latino man, were Americas favorite couple (though this was also controversial to many).

As a man who has been married to a man for several years, still living in a country were this is legal in some states but not others, and opinions on the issue differ greatly, I can understand what that was like for interracial couples at the time.

But, though I am sure there are a few hold outs here and there, I think those attitudes regarding interracial marriage have largely dissipated and this is now something that is generally accepted, even among many who once opposed it. Much as I suspect will be the case for same sex marriage.

Do you know what interracial marriage is called these days? It's call marriage. I can't wait till the same can be said of same sex marriage.

A few years ago when I was quite suggestible, I was working in retail alongside a shitty boss when a couple walked in. Black guy, white girl -- early twenties. After they left my boss went off "Look at that. The hell is she doing. Ruining her life etc etc" Typical me antagonized such a negative view by saying in jest "Mmm. I could totally see myself dating a black chick." to which he replied "Are you out of your mind? Say that to your father so he can knock some sense into you" to which I said "I don't think so. My dad's open minded" Given him and my dad were the same age, the interracial topic never came up between me and dad, and that he made that claim with such confidence, it got to me. I doubted "Was my old man that closed-minded too?"

I called him the next day. "Dad, would you have a problem if I married a girl from a different race?" and he replied after what seemed like an appropriate 3 sec pause "As long as you both have an understanding of where you come from, and accommodate your differences in culture, that's all that matters." [paraphrased] One of my favoritest moments ever. I did, of course, have to spend the next 2 minutes convincing him, "I was just asking to see what you thought. No, I am not planning to marry anyone. It was a hypothetical question! Omfg I promise!"

Race itself is a social construction. We are not different species. Neither is there such thing as a 'pure' race. We are the human race. Go back far enough and there's always DNA from other genetic sources.

The problems in such relationships usually happen because of large cultural differences or pressures from people outside the relationship.