Below is a list of the busiest days of each year for Washington's Metrorail system - as best as can be determined. The one highlighted in purple is an imperfect estimate from an online tool.
Year Event Day Ridership
2020 Hockey (18,573) Wen Mar 4 - 675,000 (suspected)
2019 CBF, Wiz (16,616), Baseball(23,050) Wen, Apr 3 - 756,500
2018 Stanley Cup Celebration Tue, Jun 12 - 840,145
2017 Women's March on Washington Sat, Jan 21 - 1,001,613
2016 Cherry Blossom Festival (CBF) Thu, Mar 24 - 767,000
2015 Baseball (41,291) Wen, July 22 - 782,707
2014 CBF, Baseball (20,869), Miley Cyrus Thu, Apr 10 - 818,076
2013 CBF, BB(24896), Wizs (20308), Immigration rally Wen, Apr 10 - 871,164
2012 CBF, Hockey (18,506) Fri, March 23 - 845,669
2011 Baseball (27,130), US Open Golf Wen, June 15 - 851,742
2010 CBF, Wizards (18,002) Fri, Apr 2 - 891,240
2009 Obama Inauguration Day Tue, Jan 20 - 1,120,000(est)
2008 Baseball (33,653), WofF conference Fri, Jul 11 - 854,638
2007 CBF/Baseball (20,894) Tue, Apr 3 - 831,508
2006 Immigrant Rights Rally Mon, Apr 10 - 821,283
2005 Baseball (36,840) Thu, July 21 - 769,553
2004 Reagan State Funeral Wen, June 9 - 850,636
2003 AofGod & Soccer (Barcelona v. Milan) Wen, July 30 - 745,627
2002 National Rally in Solidarity With Israel Mon, April 15 - 718,747
2001 No Event Thu, July 12 - 699,990
2000 Million Family March Mon, Oct 16 - 688,467 (*)
1999 CBF Thu, April 8 - 637,305
1998 The highest known day was 7/4 with 585,354, but also know it was lower than 603,766
1997 Promise Keepers Sat, Oct 4 - 725,909
1996 Highest known day: 7/4 with 569,894, but know it was lower than 688,467 if a weekday or 725,909 if not
1995 Million Man March Mon, Oct 16 - 804,146
1994 Elton John & Billy Joel concert at RFK Wed, July 20 - 603,706
1993 Clinton Inaugural 1 Wen, Jan 20 - 811,257
1992 Only know it was between 529,000 and 565,000
1991 Desert Storm Parade Sat, June 8 - 786,358 Counted by hand
1990 New Kids on the Block concert Tue, July 17 - 577,800
1989 George H.W. Bush Inauguration Fri, Jan 20 - 604,089
1988 Washington for Jesus rally Fri, Apr. 29 - 565,000 (but?)
1987 No Event Thu, June 25 - 515,047
1986 Highest known day: 7/4 with ~500,000 but know it was lower than 565,000
1985 Highest known day: 7/4 with ~550,000 but know it was lower than 565,000
1984 4th of July/ Beach Boys Concert Wed, July 4 - ~ 470,000
1983 20th Anniversary of MLK March Sat, Aug 27 - ~370,000 (suspected)
1982 Only know it was between 303,074 and 400,000
1981 Solidarity Day Sat, Sept 9 - ~400,000
1980 Rally for Jesus Tue, April 29 - ~400,000
1979 Energy Crisis Tue, June 19 - 306,059
1978 Highest known day: 9/28 with 212,524 but ridership was up to 222000 by end of year
1977 Highest known day: 10/4 with 141,319
1976 Opening Day Sat, Mar 27 - 51,260
