For my personal research

[Buttermilk]

Is there any trace of the chess game between Julio Kaplan and Danny Kopec during the 1975 American Championship in New York.
No traces of it in the various databases (ChessBase, Chess.com, NIC, etc ...)
Position seen in the LCT2 v1.21 test (POS04)

FEN : 1nr5/2rbkppp/p3p3/Np6/2PRPP2/8/PKP1B1PP/3R4 b - - bm e5; id "LCTII.POS.04"; c0 "Kaplan - Kopec, USA 1975

[AdminX]

The only game I could locate was from the year 1974

[pgn]
[Event "US op"]
[Site "New York"]
[Date "1974.??.??"]
[Round "11"]
[White "Kopec, Danny"]
[Black "Kaplan, Julio P"]
[Result "1-0"]
[ECO "B50"]
[PlyCount "101"]
[EventDate "1974.??.??"]

1. e4 c5 2. Nf3 d6 3. Bd3 Nc6 4. c3 g6 5. Bc2 Bg7 6. O-O e5 7. d3 Nge7 8. Nbd2
O-O 9. Nb3 b6 10. Re1 Ba6 11. Be3 Rc8 12. Qd2 d5 13. exd5 Nxd5 14. Bh6 Qd6 15.
Rad1 Rfd8 16. Nc1 Rc7 17. Bxg7 Kxg7 18. Ne2 f5 19. a3 Qf6 20. c4 Nde7 21. Qc1
h6 22. Ng3 Bb7 23. b4 Nd4 24. Nxd4 Rxd4 25. Ba4 h5 26. h3 Nc8 27. Ne2 Rd8 28.
f4 Re7 29. fxe5 Rxe5 30. Nf4 Rd4 31. Be8 Qd6 32. Nxh5+ gxh5 33. Qg5+ Kf8 34.
Qxh5 Rxe1+ 35. Rxe1 Qf6 36. Bg6 Nd6 37. Qh6+ Qg7 38. Qg5 Ne4 39. Qxf5+ Qf6 40.
dxe4 Qxf5 41. Bxf5 Rxc4 42. bxc5 Rxc5 43. Rd1 Bc6 44. g4 Rc3 45. h4 Rxa3 46.
Rd6 Bxe4 47. Rf6+ Kg7 48. Rg6+ Kf7 49. Bxe4 b5 50. h5 b4 51. h6 1-0
[/pgn]

Clearly not the position you are looking for ...
[d]1nr5/2rbkppp/p3p3/Np6/2PRPP2/8/PKP1B1PP/3R4 b - -

[Buttermilk]

The only game I could locate was from the year 1974

[pgn]
[Event "US op"]
[Site "New York"]
[Date "1974.??.??"]
[Round "11"]
[White "Kopec, Danny"]
[Black "Kaplan, Julio P"]
[Result "1-0"]
[ECO "B50"]
[PlyCount "101"]
[EventDate "1974.??.??"]

1. e4 c5 2. Nf3 d6 3. Bd3 Nc6 4. c3 g6 5. Bc2 Bg7 6. O-O e5 7. d3 Nge7 8. Nbd2
O-O 9. Nb3 b6 10. Re1 Ba6 11. Be3 Rc8 12. Qd2 d5 13. exd5 Nxd5 14. Bh6 Qd6 15.
Rad1 Rfd8 16. Nc1 Rc7 17. Bxg7 Kxg7 18. Ne2 f5 19. a3 Qf6 20. c4 Nde7 21. Qc1
h6 22. Ng3 Bb7 23. b4 Nd4 24. Nxd4 Rxd4 25. Ba4 h5 26. h3 Nc8 27. Ne2 Rd8 28.
f4 Re7 29. fxe5 Rxe5 30. Nf4 Rd4 31. Be8 Qd6 32. Nxh5+ gxh5 33. Qg5+ Kf8 34.
Qxh5 Rxe1+ 35. Rxe1 Qf6 36. Bg6 Nd6 37. Qh6+ Qg7 38. Qg5 Ne4 39. Qxf5+ Qf6 40.
dxe4 Qxf5 41. Bxf5 Rxc4 42. bxc5 Rxc5 43. Rd1 Bc6 44. g4 Rc3 45. h4 Rxa3 46.
Rd6 Bxe4 47. Rf6+ Kg7 48. Rg6+ Kf7 49. Bxe4 b5 50. h5 b4 51. h6 1-0
[/pgn]

Alas no, it is not this game of chess ...

[AdminX]

The only game I could locate was from the year 1974

[pgn]
[Event "US op"]
[Site "New York"]
[Date "1974.??.??"]
[Round "11"]
[White "Kopec, Danny"]
[Black "Kaplan, Julio P"]
[Result "1-0"]
[ECO "B50"]
[PlyCount "101"]
[EventDate "1974.??.??"]

1. e4 c5 2. Nf3 d6 3. Bd3 Nc6 4. c3 g6 5. Bc2 Bg7 6. O-O e5 7. d3 Nge7 8. Nbd2
O-O 9. Nb3 b6 10. Re1 Ba6 11. Be3 Rc8 12. Qd2 d5 13. exd5 Nxd5 14. Bh6 Qd6 15.
Rad1 Rfd8 16. Nc1 Rc7 17. Bxg7 Kxg7 18. Ne2 f5 19. a3 Qf6 20. c4 Nde7 21. Qc1
h6 22. Ng3 Bb7 23. b4 Nd4 24. Nxd4 Rxd4 25. Ba4 h5 26. h3 Nc8 27. Ne2 Rd8 28.
f4 Re7 29. fxe5 Rxe5 30. Nf4 Rd4 31. Be8 Qd6 32. Nxh5+ gxh5 33. Qg5+ Kf8 34.
Qxh5 Rxe1+ 35. Rxe1 Qf6 36. Bg6 Nd6 37. Qh6+ Qg7 38. Qg5 Ne4 39. Qxf5+ Qf6 40.
dxe4 Qxf5 41. Bxf5 Rxc4 42. bxc5 Rxc5 43. Rd1 Bc6 44. g4 Rc3 45. h4 Rxa3 46.
Rd6 Bxe4 47. Rf6+ Kg7 48. Rg6+ Kf7 49. Bxe4 b5 50. h5 b4 51. h6 1-0
[/pgn]

Curious to know where you found this game of chess and I say a very big thank you.

I pulled it from 365Chess.com

[Ajedrecista]

Hello Erick:

I only found the game that Ted already found. Supposing that the game was indeed Kaplan - Kopec, USA 1975 and LCTII is not wrong, I am not sure about 'American Championship' in New York. ChessGames lists 'US Championship 1975' in Oberlin, Ohio; and 'US Open 1975' in Lincoln, Nebraska; both of them without Kaplan and Kopec:

US Championship 1975

US Open 1975, Lincoln

However, there was a tournament called '1975 World Chess Open' actually held in New York. This tournament has some chances of a Kaplan - Kopec game since both of them played in this tournament according to the September, 1975 issue of Chess Life magazine. Please take a look at page 586 of that issue:

http://uscf1-nyc1.aodhosting.com/CL-AND ... 975_09.pdf

[...]

The Open Section featured an astonishing series of up-sets—perhaps more than in any previous U.S. event. The biggest surprise of all was the performance of 19-year-old Alan Trefler of Brookline, Mass., a student at Dartmouth College. Ranked 115th before the tournament with a rating of 2045, Trefler lost his first game to Orest Popovych (2295) but then won eight in a row to tie for first with Grandmaster Pal Benko (2504). In the last five rounds, Trefler defeated Lipking (2223), Frankle (2194), Wachtel (2308), Kaplan (2462), and Rohde (2296) to send his rating zooming up to about 2300 and capture a $2,250 share of the prize fund.

Grandmaster Benko, recovering from a poor showing in the recent U.S. Championship, won the same amount and took the title on tiebreak with his unbeaten 8-1 record. Benko won his first five games, drew With GM Walter Browne in round 6 and with rapidly rising young Houston Master Ronald Henley in round 7, and beat Master Danny Kopec and Expert Robert Gruchacz in the last two rounds.

[...]

Bold added by me. The only round that they would not meet each other was the eighth. Other than that, I have not found a single PGN file of the 1975 World Chess Open. I also tried some searches with descriptive notation in some Chess Life issues just in case players were not Kaplan and/or Kopec, but I was unsuccessful.

[d]1nr5/2rbkppp/p3p3/Np6/2PRPP2/8/PKP1B1PP/3R4 b - -

Do you know if ..., e5 was actually played or was it a missed move?

Good luck in your personal research!

Regards from Spain.

Ajedrecista.