Final answer:
The bolded sentence underscores the economic significance of the modern travel industry and its impact on various trades, highlighting the transformation of transportation over time.
Step-by-step explanation:
The bolded sentence from the 'A Chat with The Editor' in the 1954 Edition emphasizes the vast expenditure on travel and the economic impact of the travel industry. It highlights the transformation of the transportation landscape from an era dominated by the train, bus, and steamship to a time when personal automobiles and air travel became prevalent. The sentence underlines how modern transportation has made it possible for people, including African-Americans, to explore the world, stimulating economic growth through revenue generated by tradespeople linked to the travel industry. It emphasizes that travel is not just a means of movement but a significant economic sector that affects various aspects of society and commerce.