How would you say American culture in general and pop culture (movies, music, etc) changed between 1970 and 1979? What was the general atmosphere in the early 1970s (1970-1973), Mid 70s (1974-1976) and late 70s (1977-1979)? It just seems to me that there was a very different tone to each part of the decade, more than most decades, but, what do you think in your opinions?

  Early 70's were like the 60's...long hair, protest songs, grubby bell bottom jeans, pot and acid. Late 70's were still long hair, disco songs (yuck), still bell bottoms but they were cleaner, pot and cocaine. The middle years were sort of a transition.

Your assertion that the early, mid, and late 70s were all different is correct.  I don't know for sure if the 70's saw more changes than other decades; it's possible, though.

One could write a whole book on this topic, but I'll just pick one or two subject areas.  Since I was a teen during the decade and not older, I have only certain recollections anyway.

American experience: in the early 70's, there was a lot of pie-in-the-sky optimism about what we could do (since we just put a man on the moon) juxtaposed against the rage of the young, and there was tension between the "hippies" versus the "establishment".  Drug use was rampant and not getting better.  We worried about the war and the environment and societal ills like poverty and crime and drugs and racism.  A couple years in (around when Nixon got reelected) "hippies" started getting disillusioned.  At that time there was still a military draft, up until 1973.  As Watergate slowly took down the Nixon administration, cynicism set in.  Ford brought a welcome change, but then we were beset by economy problems especially the oil embargo, that caused the first feelings that we weren't as in control as we needed to be.  Cars began shrinking - foreign cars began selling - and Detroit was taken down a notch.  The Ford years really weren't so bad in hindsight.  Drug abuse was going down but crime was high.  Then, high hopes accompanied Carter into his presidency - but he quickly showed himself to be a disappointment.  Runaway inflation was on everyone's radar, and many businesses found it hard to flourish at that time.  There was a sense the country was getting weaker - especially when Iran took American hostages.  The sense of helplessness boggled the mind of those who earlier in the decade felt invincible.

One thing that improved throughout the decade was the stature of both minorities and women.  It wasn't as much through legislation, either - it was that people's minds actually began to change.  A very good thing.

This topic has been discussed before:

http://www.inthe00s.com/index.php?topic=38129.0

  I agree with American Girl, who, the more I read her, the more I think we were soul mates who should have met each other 35 years ago, but anyway...the 70's were a great and fun time to be young, but they really sucked in terms of world events.
  The early years started out with Vietnam, became Watergate, became Ford (inflation, energy crisis,) became Carter (high interest rates, still more inflation, now the Muslims were giving us the finger, general malaise.) And Cambodia was having a genocide, England was suffering through a terrible economy, strikes etc.
  Fortunately for those of us still young, it was a time of the greatest music ever, and selfishly speaking, it was a time when the girls began to get "playfull."