So, yesterday was Groundhog Day and so we watched Groundhog Day. And since, the last time I searched, I did not come across an obsessive timeline of the sort that I have come to expect from the interwebs in re the likes of Back to the Future and Terminator, this time I took notes on how many days had actually passed.

These are the days actually seen in the movie:

1. February 1
2. February 2, #1
3. "You're playing yesterday's tape"
4. "Meet me in the diner", "Don't drive on the railroad tracks"
5. Punches Ned
6. "Nancy Taylor, Lincoln High!"
7. Bank robbery -- "I've seen this film over 100 times"
8. Interrogating Rita
9. "Sweet vermouth on the rocks with a twist"
10. "I like to say a prayer and drink to world peace"
11. "I studied 19th century french poetry." (He has a good French accent on the quotation, and is a good dancer.)
12. Insincere snowman. Slapped in the face.
13. Slapped in the face.
14. Slapped in the face.
15. Slapped in the face.
16. Slapped in the face.
17. Slapped in the face.
18. Slapped in the face.
19. Slapped in the face. Notices ice sculptures.
20. "Rough night."
21. "It's cold out there every day."
22. "What is... Mexico."
23. "A thousand people waiting to worship a rat."
24. Smashes clock.
25. Smashes clock.
26. Smashes clock on floor, kidnaps groundhog, blows up.
27. "Aw nuts." Drops toaster in bathtub.
28. Steps in front of truck.
29. Jump from bell tower.
30. "I'm a god." "I've been stabbed, shot, poisoned, frozen, hung, electrocuted, and burned." Throwing cards: "Six months, four to five hours a day."
31. Gives money to bum. First piano lesson.
32. Second piano lesson.
33. Has learned ice sculpture.
34. Not bad at piano.
35. Hits on Ned, takes bum to hospital.
36. Feeds bum, gives CPR.
37. Final Groundhog day! Very good at piano.
38. February 3.

Now, beyond the days we actually see, much time is implied:

• Between days #6 and #7, at least 100 days passed: the time to see the movie 100 times, and also to fully memorize the plan for the bank robbery.

• Between days #11 and #12, he may have just memorized a single quotation (but his accent is good) and he may have already known how to dance (but that seems unlikely). So I think we can assume at least a few months passed.

• Between days #21 and #22, he memorized the entire Jeopardy show, which would take at least a few viewings. It's possible he did that while learning piano, or French.

• Some time before day #30, six months of card throwing. But that could have all been after midnight, and overlapped with any other activities.

• We saw "burned" and "electrocuted". That leaves at least five days (and presumably more) for "stabbed, shot, poisoned, frozen, and hung."

• How long does it take to learn ice sculpture, if that's all you do? Six months? A year?

• How long does it take to become a good piano player, if you begin in your early 40s when you have your first lesson? Concensus among those present at casa del jwz was "at least two years."

So.

Based on evidence presented in the movie, he re-lived February 2 for at least four years.

The Wikipedia entry says ^{[citation needed]} that "director Ramis has stated Phil repeats the day for about 10 years, noting that it would take that long to become as proficient on the piano as Connors does from daily lessons, though the original script had February 2 repeating for ten thousand years."

Which answer, you know, I found insufficient.

Update: We now have as authoritative an answer as we're likely to get: Danny Rubin, the guy who wrote Groundhog Day, wrote on his blog that he had no intended time-frame in mind in his script, but that he meant for it to be "more than one lifetime". The studio hated that, and said, "that's too long, make it two weeks". Harold Ramis, the director, tried to make the time-frame ambiguous, but had in his mind "ten years".

Incidentally, this year the rat saw its shadow.