1. In the early 1900s (around 1900-1910), a substantial sum of money could be considered around $1,000 or more.
2. During World War I (1914-1918), the cost of living increased, so a significant amount of money might be around $5,000 or higher.
3. In the 1920s (the Roaring Twenties), economic prosperity led to increased wealth, and substantial sums could range from $10,000 to $50,000 or more.
4. During the Great Depression (1929-1939), money became scarce, and even a few hundred dollars could be considered a significant amount.
5. In the post-World War II era (late 1940s and 1950s), economic recovery brought increased wealth, and substantial sums might range from $10,000 to $50,000 or more.
It's important to note that the context and value of money can change over time, and these examples are just rough estimates based on historical accounts.