Final answer:
The year 1968 was explosive due to significant political upheavals, widespread protests addressing diverse societal issues, and the assassinations of key leaders which combined to mark a pivotal shift in American culture and politics.
Step-by-step explanation:
The year 1968 was indeed explosive in American history for several reasons. Politically, it was a year of significant upheaval, further emphasized by the presidential election which saw candidates such as Eugene McCarthy and Hubert Humphrey vying for the Democratic nomination amidst President Johnson's decision not to seek re-election.
Socially and culturally, the year was marked by profound disruptions, as citizens across the United States engaged in widespread protests. Issues raised by these protests ranged from the Vietnam War, racial equality, environmental concerns, to a rethinking of societal norms, including challenging the paternalism within marriage and the objectification in beauty pageants.
Internationally, the climate was no less turbulent. The assassinations of key leaders, the ongoing Vietnam War, and the global wave of protests, notably the student-led Prague Spring which was crushed by the Soviet Union, and the May 1968 events in France, profoundly influenced the American political and social landscape.
The increasing awareness and demands for change in areas such as civil rights, feminism, and anti-war sentiments foreshadowed a period of reformation and conflict, making 1968 a year that represented a significant shift in American culture and politics.