Why did Star Trek only have 3 seasons?

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Tags

1. #throughout
2. #while
3. #seasons
4. #canceled
5. #status
6. #episodes
7. #series
8. #several
9. #1970s
10. #popular
11. #later
12. #network
13. #became
14. #three
15. #classic
16. #developing
17. #achieving
18. #syndication
19. #nielsen
20. #influence
21. #broadcast
22. #culture
23. #after
24. #ratings
25. #remaining
26. #years