The New Age movement is typically seen by religious studies scholars and American religious historians as a relatively modern development of what is termed metaphysical religion in the United States. American religious historians used to use a variety of terms to describe metaphysical religion; it has been called occult religion, and harmonial religion. Metaphysical religion has a long pedigree, for the most part existing outside established religious institutions and emphasizing individual experience.

In 1600s England, a group sprang up that was deeply interested in what purported to be ancient writings by a mysterious Egyptian or Greek figure called Hermes Trismegistus (modern scholars dispute the authenticity of these writings). This hermetic tradition emphasized that initiates could get access to secret knowledge of the world that could improve their health and status. There was also a robust community dedicated to alchemic lore, and alchemy practitioners tried to achieve immortality and create wealth. There was also some interest in Kabballah, which sought to strip this mystical practice of its original Jewish religious context.

Metaphysical ideas were imported to the British colonies in North America. A 1697 estate inventory of Reverend Thomas Teackle of Virginia for example reveals that he had a library of books on alchemy, hermeticism and other occult ideas. The Puritans were both deeply interested in and fearful of magic, and it was fairly common for people in New England to possess books containing a mix of folklore and information of magical practices.

The nineteenth century saw a large number of new kinds of metaphysical religious beliefs and practices appear in the United States. Spiritualism, a belief in the ability of the living to communicate with the dead, was perhaps the most popular of these ideas. By some estimates, over 11 million Americans embraced some aspect of spiritualism, and the enduring popularity of seances and psychic mediums attests to the movement’s lasting influence.

New Thought was one particularly important manifestation of metaphysical religion. Appearing at the end of the nineteenth century, New Thought taught that mental energy had the ability to affect reality, for example to provide healing or to generate wealth. This was often called The Law of Attraction; in contemporary society it has been popularized by the book and film The Secret. Many of the ideas of New thought found their way into Christian Science, a religious denomination that taught that physical reality was an illusion and that faith and mental power could cure disease and illness.

New Age beliefs relied heavily on existing metaphysical religious ideas. The notion of energy healing for example, built on many of the concepts about healing already advanced in New Thought. Belief in UFOs was spurred in part by connections with theosophy, a nineteenth century religious movement that tried to fuse Buddhism, Hinduism, and European esoteric ideas. Theosophy’s leader, Helena Blavatsky, taught the ideas for the movement had been psychically communicated to her by beings from the planet Venus. At least some of the people who claimed to have had direct encounters with aliens in the 1950s were affiliated with the theosophy movement, and the I AM movement, one of the first UFO based new religious movements, came out of theosophy.

None of this should be taken to mean that there was nothing novel about New Age practices, as the 1960s were a fertile time for religious development. Increased knowledge of Hinduism and Buddhism probably shaped New Age practices, as did new scientific developments. Belief in UFOs was at least partly shaped by the space race and advancements in aeronautic technology. Yet the New Age was just one part of a long legacy of metaphysical religion in the U.S.

Suggested Readings:

Albanese, Catherine L. A Republic of Mind and Spirit: A Cultural History of American Metaphysical Religion. New Haven, CT: Yale University Press, 2007.

Kripal, Jeffrey J. Esalen: America and the Religion of No Religion. University Of Chicago Press, 2007.

Partridge, Christopher Hugh. UFO Religions. Psychology Press, 2003.

During the 1960s and 1970s there was a revived interest in occultism and alternative spirituality in the United States. This was not a single organized movement, but the coming together of several strains of thought that had their roots back in the revived interest in occultism and spirituality during the Third Great Awakening in the late 19th and early 20th century.

Why and how is a little difficult to name. The rise of occult interest also coincided with the general increased interest in fantasy, sword & sorcery, weird fiction, and science fiction - these were the decades when The Lord of the Rings hit paperback, the works of H. P. Lovecraft and Robert E. Howard hit paperback, Star Trek went on the air and then off the air and into syndication. Prominent figures in popular culture like the Beatles began exploring Eastern religions, continuing a trend that glamourized figures like Aleister Crowley (who appeared on the cover of Sergeant Pepper's Lonely Hearts Club Band), new religious movements like Wicca gained prominence and organization, writers like William S. Burroughs emphasized the search for new pharmaceutical experiences in The Yage Letters, head shops and psychedelic art and literature emphasized visionary experiences and mysticism, Doctor Strange debuted in the comic books...

...lots happened, often at the same time. Sociologists and psychologists can argue the reasons why, but generally speaking there was a rising interest in the occult, which in turn fed a growing amount of art, literature, and media in the occult. Asking which came first is a bit of a chicken-and-egg; availability and appetite were both there. For both good and ill; the same general impetus that gave us Scientology and Black Metal also gave us Jonestown and the Manson Family. But outside the actual cults and new religions, there were a lot of widespread beliefs which can mostly be traced back to earlier ideas and movements.

If you want to do some more general reading, I would recommend:

• Turn Off Your Mind: The Mystic Sixties and the Dark Side of the Age of Aquarius by Gary Lachman (not scholarly, but very readable)

• High Weirdness: Drugs, Esoterica, and Visionary Experience in teh Seventies by Eric Davis

• The Cult of Alien Gods: H.P. Lovecraft And Extraterrestial Pop Culture by Jason Colavito

As for specifics:

crystals

Belief in the natural or supernatural abilities of crystals and gems goes back into prehistory; the idea of magical or scientific uses for crystals as channels or stores of energy found expression in science fiction (possibly in part because of the use of piezoelectric crystals in early radios). Details on how crystal healing developed and spread is not well documented, it appears that there were several different traditions of esoteric thought - Western occultism, Ayurvedic medicine, Native American practices (real or fictional), homeopathic medicine, and possibly even science fiction and fantasy - were all borrowed from by different authors and practitioners, but the practice appears to be highly individualistic.

aliens

Pretty much all the interest in aliens originally came from science fiction; Colavito makes a strong argument in his book that the pulps in particular shaped the imagery and literature of the early UFO enthusiasts, particular those who followed the "Shaver Mystery" (a complicated affair that began in the 1940s when Richard Sharpe Shaver published some fantastic stories about an interior world in Amazing Stories which he claimed were true experiences). The pulp origins of this kind of thing aren't that weird, I touched on this in What are the origins of the lizard-people conspiracy theory?. With UFOs in particular, there was a heavy crossover between the pulps and the early UFO enthusiast community; stuff like the Roswell incident (which happened in 1947) only really started to gain interest in the late 70s, when those folks on the fringe started publishing books on it, which reached a wider audience and a place in popular culture.

energy healing

There are two different branches for this: medical quackery and occultism. The advent of new advances in science and technology in the early 20th century led to a boom in supposed magnetic, electrical, radio, and radioactive cures; the least harmful of these were simply fraudulent, like Albert Abrams' radionics, which claimed to be able to diagnose and heal people from a distance using radio waves; you might compare with the E-meters of Dianetics/Scientiology.

The occultist angle includes the New Thought movement of Christian Science and various esoteric disciplines - there's a lot of crossover with crystals in that regard; practitioners tend to borrow ideas from Ayurvedic medicine such as chakras, meridians, etc. The general idea of life force, life energy, etc. had been fare for science fiction and fantasy for well over a century, you might look at Vril, the Power of the Coming Race (1871) by Edward Bulwer-Lytton as one example.

As with crystals and crystal-healing, "energy healing" was (and is) a confusing mish-mash of sometimes conflicting ideas and traditions, all of which had their influence and adherents, from the true believers to the hucksters, and it isn't always easy to tell the difference between the two.

how prevalent were they in the US before the 1960's?

Pretty much all of the individual ideas involved in New Age movements of the 1960s and 70s had their origin in ideas that were already present in the United States previously. What was largely new was widespread popularity; fringe beliefs suddenly had bigger audiences, who syncretized, synthesized, and produced new ideas of their own. H. P. Lovecraft's fiction, for example, was known to occultists since the 1930s, but an actual Necronomicon didn't appear until 1977, at the Magickal Childe shop in New York City. By then, there was already a psychedelic rock band named H. P. Lovecraft. You can also see this "popularizing" effect in the association of the inverted cross with Satanism.