Oops, it doesn't look like 'record for the largest single day' is a national day..

Other days

boyfriend

Boyfriend Day
lost sock memorial

Lost Sock Memorial Day
latina equal pay

Latina Equal Pay Day
african immigrant and refugee hiv and hep awareness

African Immigrant And Refugee Hiv And Hep Awareness Day
hiv awareness

Hiv Awareness Day
ruby

Ruby Day
tell ur crush you like them

Tell Ur Crush You Like Them Day
artists

Artists Day
ask out your crush

Ask Out Your Crush Day
reading

Reading Day