To determine which event caused the total number of immigrants in the United States to decrease to below 700,000, we need to examine the data provided for each decade and the historical context of the mentioned events. Here’s how we can solve it step-by-step:
1. Review Immigration Data: Let's look at the immigrant numbers by decade:
- 1820: 128,502
- 1840: 538,381
- 1860: 699,375
- 1880: 4,248,203
- 1900: 3,694,294
- 1920: 2,814,554
- 1940: 1,427,337
- 1960: 856,608
- 1980: 3,213,749
- 2000: 4,295,510
2. Identify Drop Below 700,000: We need to pinpoint the decade where the total number of immigrants dropped below 700,000. From the data, we see:
- 1860: 699,375
3. Analysis of Historical Context: We need to now match this significant drop to relevant historical events:
- World War II (1939-45): Immigration numbers in 1940 show 1,427,337, which is above 700,000.
- Cold War (1945-91): This spans a long duration where immigration numbers were again above 700,000.
- Korean War (1951-53): By 1960, the numbers were 856,608, still above 700,000.
- Vietnam War (1954–75): Immigration numbers recovered to 3,213,749 by 1980.
4. Correct Decade Identification: From the data:
- The significant drop to below 700,000 is exclusively in the year 1860.
5. Historical Event Around 1860:
- Although the options provided do not offer a corresponding event around that period, it’s worth noting that the American Civil War (1861-1865) might have had a significant impact during the early 1860s.
Based on the provided options, though none of them directly explain the drop in 1860, the correct approach would involve recognizing that none of the given options pertain to that period. The provided data seems incorrect for the available choices, but historically, the Civil War would be a key event contemporaneous to that drop.
However, to answer strictly based on the provided options without adding assumptions, none of the options correctly match the drop to below 700,000 noted in 1860.
So, none of the provided events (Vietnam War, Korean War, Cold War, World War II) caused the decrease below 700,000 as per the extracted data. The possible reasoning lies outside those given options, specifically in the period pre-dating these events, likely pointing to the Civil War era (1861-1865).
