Tomorrow, over a million NYC public school students will not be in school, sending their parents and caregivers into a frenzy of "Oh, crap, I totally forgot about this random day off a few weeks before the school year ends." And it's all because of a tradition that started back in 1829 to celebrate the founding of the first Sunday school in Brooklyn and Queens.

Called "Anniversary Day" in the Department of Education these days (PDF), the day is also known as "Brooklyn-Queens Day." The Queens Public Library once explained, "Brooklyn-Queens Day originated as a Protestant holiday celebrated in the City of Brooklyn in 1829. Back then it was known, and fondly remembered by some, as Anniversary Day. Anniversary Day is celebrated annually on the first Thursday in June, commemorating the founding of the First Sunday School on Long Island. The first parade was held in Brooklyn June 1829. The New York State Legislature enacted, in 1959 at the request of the Queens Federation of Churches, the bill permitting the schools in both Kings and Queens Counties to be closed on this day. It was signed by Governor Nelson A. Rockefeller."

Back in 2007, we looked at some historical coverage of the day:

A quick survey of the archives of the Brooklyn Daily Eagle, placed online by the Brooklyn Public Library, reveals a story of a widely celebrated religion-themed public school holiday that eventually succumbed to the changing demographics of Brooklyn and Queens. The figures and accounts are exclusive to Brooklyn, an independent city until 1898, but we imagine parallel events were occurring in Queens. The following are brief descriptions of newspaper articles that we found to be just the tip of the iceberg of what the library's archive project offers.

May 29, 1861 - "THE ANNIVERSARY, Grand Rally of the Brooklyn Sabbath Schools -- Patriotism Rampant"
In good weather, twenty-thousand children parade in separate contingents from Eastern and Western Brooklyn towards City Hall and then Fort Green. The Western Parade Marshall is identified as "Mr. Douglass," who may have been abolitionist Frederick Douglass.

April 12, 1890 - "CHILDREN'S DAY, The Anniversary Parade for June 4"
Outlining plans for the celebration, 75,000 kids are expected to march in a parade celebrating the establishment of Sunday Schools. A portion of the parade route is talked of being moved to Cumberland St., because the heavily cobbled stones on Clinton Ave. were impossible for kids to walk on and they had to detour onto Clinton's sidewalks in prior years. The paper prints celebratory hymns, but reminds readers that they are property of the "Brooklyn Sunday School Union."

May 23, 1899 - "HOW LOCAL SCHOOLS GOT AROUND THE LAW, Phases of the Anniversary Day Problem Which Has Caused So Much Trouble"
A year after consolidating itself into the greater City of New York, there is grumbling in Brooklyn about the celebration of a day which previously would be a "holiday granted without question." "This year the question of an Anniversary Day holiday became a business proposition to the board solely." There is squabbling about making it a half day, as members of the Brooklyn School Board and the Central Board contest the holiday. At issue is school funding, which is reduced if kids get the day off. A proposal is raised to consult with the Sunday School Union to move Anniversary Day to a non-school day.

Children at the 1944 Brooklyn-Queens Day Parade (Library of Congress)

February 11, 1900 - "ANNIVERSARY DAY PARADE, "Members of the Brooklyn School Board Regret Unwillingness of Sunday School Union to Compromise" Relations between the School Board and the Sunday School Union becomes adversarial when the latter refuses to change the date of the celebration from a school day. Consolidated Brooklyn can no longer grant exclusive holidays to its students without losing funding.

April 27, 1902 - "AGAINST ANNIVERSARY DAY, 'An American Mother' Points Out Its Unfairness to Those Concerned in Parade"
A letter to the editor, in response to a separate letter from "A Brooklyn Mother" who presumably is in support of the holiday, protests that the religious nature of Anniversary Day that applies to 10% of Brooklynites violates the non-sectarian nature of public schooling.

May 27, 1902 - Letters to the Editor
A number of letters to the editor decry the decision of the School Board to discontinue making Anniversary Day a school holiday.

In 2005, the United Federation for Teachers negotiated to have the day off, and in 2006, students in all five boroughs "celebrated" Anniversary day. Teachers and school staff are working—it's a "development day."

So, if you find yourself wondering why the subways are suddenly filled with kids during school hours tomorrow... now you know.