Nationals Park will also sell Canadian favorite poutine in an homage Jarry Park, the former home of the Expos.
The Nationals will honor the Montreal Expos on July 6 by donning powder blue uniforms and tri-color caps, according to the Washington Post's Scott Allen.
Washington will break out the classic uniforms to celebrate the 50th anniversary of the Expos' inagugural season in 1969. The visiting Royals will also wear throwback jerseys on July 6, sporting their gray road uniforms.
The Nats will also break out a slate of Canadian delicacies for the throwback event, per Allen. Nationals Park will sell poutine as well as Montreal smoked beef brisket sandwiches.
Former Expos legend Vladimir Guerrero is expected to be in attendance along with ex-Montreal players Dave Martinez and Bob Henley. Martinez is currently Washington's manager while Henley is the pitching coach.
The Expos played their final year in 2004. The Nationals were created in 2005, reaching the playoffs four times in the franchise's 14 seasons.