Our history is important. Below is an excerpt from the "Sacred Writings of Roscoe," which tells why we traditionally hold Worldcons as close to Labor Day as possible. In ancient times, we celebrated on Roscoe's other day. Or peruse the complete "Sacred Writings".
Roscoe watches out for stfen wheresoever they may be,
from the canyons to the desert, from the mountains to the sea.
He's a kind and helpful beaver, aiding fen in many ways,
and he merits fannish worship on the Sacred Beaver Days.These days are two in number: one's the fourth day of July—
it's the day when Roscoe flies a fiery spaceship in the sky.
In his honor, on that date, a truce should fall on fan dissension,
and every true disciple should assemble in convention.The second day is Labor Day, the date of Roscoe's birth,
when tribute should be paid him over all the fannish Earth,
when all fen shall meet their fellows to look back upon the year
and shall drink a toast to Roscoe in that other great ghod: Bheer.— Arthur Rapp (excerpted from Spacewarp #27, June 1949)
Reprinted in Noreascon 4 Progress Report 4
July 2003