There's a great article in Bloomberg BusinessWeek that while several years old does a great job at discussing how the global strategy consulting industry got started, why Boston Consulting Group was founded, how Bain was a spinoff of BCG, and how Bain Capital was a spinoff of Bain.
Although the article's title focuses on tracing the business career of Mitt Romney, currently a US Senator from Utah and at the time this article was written was candidate for U.S. President, it ends up providing a history of how BCG, Bain and Bain Capital all came to be. (These were all firms where Romney worked.)
It's an insightful article in part because it provides helpful context in understanding how big business operated back then (as well as today) and how 20- and 30-year-old consultants back then implausibly influenced clients typically double their age.
The answer to that question from the 1970's is the same as it is today. Some things do not change, and those "things" are the exact same data-driven, analytical skills that I emphasize as being critical to passing the case interview and performing as a new consultant.
While I'm sure you've heard me emphasize these points countless times, it's useful to hear corroborating data points from former CEOs and Harvard Business School professors, and examples of how these skills were used in the last 40 years of U.S. business history.
In short, I tell you these skills are useful, this article gives you the background to fully appreciate why these skills are useful.(Note: The article begins by describing Mitt Romney's 2012 US presidential campaign, but by the middle of the first page discusses the history of the strategy consulting industry.)