Today’s Washington final between Milos Raonic and Vasek Pospisil is the first all-Canadian final in the Open era. Here’s a list of the other 20 countries that have represented both sides of an ATP final, along with the total number of such finals and the most recent such match:
- SUI (2)
2014 Monte Carlo Masters: Stanislas Wawrinka d. Roger Federer, 4-6 7-6(5) 6-2 - ESP (94)
2014 Houston: Fernando Verdasco d. Nicolas Almagro, 6-3 7-6(4) - FRA (21)
2014 Montpellier: Gael Monfils d. Richard Gasquet, 6-4 6-4 - GER (9)
2013 Munich: Tommy Haas d. Philipp Kohlschreiber, 6-3 7-6(3) - ARG (25)
2012 Santiago: Juan Monaco d. Carlos Berlocq, 6-3 6-7(1) 6-1 - SRB (1)
2011 Moscow: Janko Tipsarevic d. Viktor Troicki, 6-4 6-2 - USA (448)
2011 Atlanta: Mardy Fish d. John Isner, 3-6 7-6(6) 6-2 - AUT (7)
2010 Vienna: Jurgen Melzer d. Andreas Haider Maurer, 6-7(10) 7-6(4) 6-4 - CRO (2)
2009 Zagreb: Marin Cilic d. Mario Ancic, 6-3 6-4 - RUS (4)
2006 Moscow: Nikolay Davydenko d. Marat Safin, 6-4 5-7 6-4 - BEL (1)
2006 Munich: Olivier Rochus d. Kristof Vliegen, 6-4 6-2 - AUS (71)
2003 Scottsdale: Lleyton Hewitt d. Mark Philippoussis, 6-4 6-4 - SWE (30)
2000 Long Island: Magnus Norman d. Thomas Enqvist, 6-3 5-7 7-5 - CHI (3)
2000 Orlando: Fernando Gonzalez d. Nicolas Massu, 6-2 6-3 - NED (1)
1995 Rotterdam: Richard Krajicek d. Paul Haarhuis, 7-6(5) 6-4 - BRA (2)
1992 Sao Paulo: Luiz Mattar d. Jaime Oncins, 6-1 6-4 - ITA (5)
1988 Florence: Massimiliano Narducci d. Claudio Panatta, 3-6 6-1 6-4 - CZE (2)
1976 Basel: Jan Kodes d. Jiri Hrebec, 6-4 6-2 6-3 - NZL (2)
1975 Auckland: Onny Parun d. Brian Fairlie, 6-2 6-3 4-6 6-3 - ROU (1)
1972 Omaha: Ilie Nastase d. Ion Tiriac, 2-6 6-1 6-1
Heavy Topspin: A Tennis Blog 
Nice list. And another interesting first this weekend — first final(s) between players born in the 90s. Would be interesting to see a comparison with previous decades if you have the information, to illustrate how much later players are breaking through