>>1476535>Why couldn't they coexist?Cheap airlines basically killed an entire customer base for the ocean liner industry, steerage. Instead of spending 4-5 days on an passenger ship, immigrants and people on cheap business trips could take the same journey in 8-10 hours at comparable if not cheaper prices (not to mention no need for spare clothes, paying for meals and the like). That basically only left the wealthy and those looking for a vacation as their only real remaining customer base, hence the rise of cruise lines.
Not to mention as
>>1476552 mentioned, the ocean liner industry had already taken a massive hit when the National Origins Act of 1924 was passed, curtailing immigration, even more so when the US became Ground Zero for the Great Depression. The two leading British companies, White Star and Cunard were on the verge of insolvency and had to be merged in the 1930s to prevent their collapse.
There was a brief boost in demand following the end of WWII as survivors of the Holocaust and the general absolute dumpsterfire Europe was in 1945 began moving abroad, but then the Cold War set in and Western Europe experienced an economic ressinance as a result of the Marshall Plan (the Eastern European market on the other hand was firmly locked behind the Iron Curtain) and the largest market for ocean liners (Europe-to-the-United States) largely whittled away, those few immigrants who did come generally preferred to travel by air by the time of the 1960s.
tl;dr we have three main causes
-Rise of rabid xenophobia in the United States that led to extreme restrictions on immigration that were not repealed until 1965
-Western Europe becoming rich again following WWII (to the point where they now have a higher standard of living than the United States in many respects) and Eastern Europe being effectively closed off to immigration entirely
-Rise of the Airline Industry
