Casper has nothing but amity and kindness in mind; it is no coincidence that his second, long-delayed cartoon appeared during the year of the famous Berlin airlift (1948). Casper is therefore an unconscious representation of America's self-image during the post-WWII era. It's not a perfect metaphor, but it is totally reflective. There is one moment in US history, however, where cartoons missed their connection with society.
It is difficult to summarize 1968 in a single paragraph when entire books have been written about that year alone. Race riots in cities large and small; campuses aflame in protest; King and Kennedy laid low by assassins; the senseless draining of blood and money into the morass that was Vietnam; a president who shied from re-election rather than face the humiliation of a disillusioned public; social engineering programs that seemed to inflame rather than alleviate injustices. A Democratic convention that exploded into spectacular violence; America's generations rent apart. Finally, there was the election of a brilliant but thoroughly demonic president whose paranoid and dishonest machinations eventually destroyed him.
The animation studios barely noticed. During some the worst social and political upheaval ever experienced in America, cartoons seemed to be heedless of the chaos, like fish swimming placidly below the ocean's surface while ship-sized waves raged above. The year 1968 produced virtually no response or reflection with what was happening in American culture. In present times, animation can present nearly instant parody or commentary (as the case may be). Why, in 1968, did animation seemingly turn a blind eye to shattering events that flooded the news almost daily?
The Terry studio was gone by 1969, but its offerings for 1968 largely featured Sad Cat, a justifiably forgotten nebbish. Walter Lantz stayed in business until 1972 with nothing to say about the fracturing of his country. A 1971 Woody Woodpecker cartoon titled The Reluctant Recruit featured Woody Woodpecker attempting to escape the French Foreign Legion, This was not an analogy for draft resistors, unless one was smoking whatever Jerry Garcia was smoking. There were stirrings at Paramount, where Ralph Bakshi  had begun to explore the counterculture in his cartoon shorts, but the studio was kaput by 1967.
TV in 1969 was not much better. Superheroes virtually disappeared from the Saturday morning scene, to be replaced by countless "hip" cartoons featuring rock bands, and I won't even bother to compare them to Jefferson Airplane or The Doors. Much the same for 1970. Colorful psychedelics were acceptable, but the specter of subversive rock was not. In fact, it was not until 1972 that Bill Cosby and the Filmation studio addressed race and socioeconomics with Fat Albert and the Cosby Kids. That same year Ralph Bakshi unleashed a horny tabby named Fritz on the big screen but by then the Vietnam War would bleed America for only one more year and Richard Nixon was well on the way to his historic disgrace.
So, what prevented animation from reflecting the cultural zeitgeist? As usual, complicated answers have no single explanation, but are rather found in a confluence of factors. For one thing, animation was never a rich source of political commentary in America, and thus no historical basis for statement existed. This is unusual, since the US did not have to deal with state ownership (and censorship) as many overseas animation companies did. The nation that prided itself on principles of free speech rarely used it in animation, largely because cartoons were used for entertainment. Perhaps John Hubley  had the best chance of expressing political views in 1960s America, but he had already been bloodied by HUAC in the decade before. Thus, there was neither radicalism nor reactionary content in our cartoons.
If one was part of the machinery of TV studio animation during 1968-70, there was damn little time to protest the war, express racial solidarity or advocate for victory over the Viet Cong. Although many animators undoubtedly had preferences and would take to the streets for them, said animators were busy trying to meet crushing production schedules and footage quotas. Since the work was seasonal, the same animators were dealing with layoffs and ways to keep meals on their tables once a season of cartoons was completed. Their wealthier brethren in Hollywood had the time and comfort to practice chic radicalism or to defend Nixon and his presidency; animators struggled to keep themselves fed.
Eventually animators and their beleaguered unions fought bitter battles for residuals but lost the war in 1969-70; animation producers were able to exploit divisions between different job positions in the industry. Soon, animation would be farmed out to foreign markets, further weakening animator's positions and stunting the unions. One generally does not participate in, or find flaming passion for, activism when the wolf is halfway through the door.
The studios themselves, outside of labor issues, were largely apolitical. They were a business, centered on producing a commodity and making profits. They were not the sort of venues that bred political activism. Although creativity flourished inside their walls, animation studios were not universities, steamy ghettos, police headquarters, smoke-filled convention rooms, ROTC programs or drop-in vet centers. Except for Jay Ward  (who eventually tired of overreaction to his sharp-witted parodies), most studio heads and producers concentrated on getting shows on the air, setting production deadlines, finding sponsors, and conducting commerce. Although artists are traditionally seen as unconventional, even somewhat radical, Hollywood's animators had a hard time being among them.
In truth, many of them in lead positions were relics of an earlier period of animation -- and American history. Veterans of the theatrical studios, they represented an old guard that were astonished by race riots, campus unrest, women's liberation, draft-card burnings and a gory war that was found to be based on lies and deception. They were lifetime professionals, unsurpassed in experience and knowledge, not the type to take to the streets, grow long hair and beards or don hard hats and batter hippies. So they didn't. Animation was an unusual business, both creative yet insular during the strange times of the 1960s.
A final factor was technology, or rather, its limitations. Anyone who wanted to make independent or group commentary on the events of 1968-70 had to do so after hours or during periods of unemployment with limited resources, using the traditional tools of animation. There were no computers, no programs, no software, no Maya, no Flash, no pixels, wireframe, nada. As much as one wanted to defame bearded protesters, excoriate the perpetrators of Vietnam, or condemn/support segregation or busing, one had to face the fact that it would take months of out-of-pocket work in order to do so. At roughly $500-$800 per week, the going rate for animators at the time, it was too expensive to protest, especially when facing layoffs at the end of production season. That money had to be carefully hoarded. And so animation and popular culture parted ways in 1968, one of the nation's most significant and fractious years in a decade rife with them.
Without even playing the game of muddle-minded deconstructionism, one can find many examples of how animation from 1914-2000 flowed in concert with the American zeitgeist. After 2000, cartoons no longer seemed to operate in symbolic fashion; it was as if the entire Freudian concept of unconscious symbolism disappeared and our dreams spoke to us without obfuscation. Animation today places its political and moral agendas directly on the table with little subtlety.
This is neither good nor bad; it simply signals a shift in how our society processes messages and information. News is instantaneous. A video taken on a cell phone can be disseminated worldwide in minutes. E-mail is looking increasingly Jurassic. Most communication preferred by the younger demographic is now contained in 140 characters or less, and some people are "friended" upwards of 500 times. Nothing of political significance in this country is ever likely to be overlooked by animation again, not with our current technology, the passionate acrimony of partisan politics and the number of media outlets now available to the public.
Sadly, there is a nearly blank record of 1968's legacy. No theatrical animated features or standard cartoon TV fare truly reflect the turmoil of the times. If you seek the animated legacy of America's most terrifying period of cultural and political disorder, you won't find it. In its stead was Scooby Doo, Where Are You? 
Martin "Dr. Toon" Goodman is a longtime student and fan of animation. He lives in Anderson, Indiana.