This parade which has been going on for about 30 years is the Solstice Parade. It was not a gay rights parade but it did have naked cyclist's when I attended some years ago. This is typically for Freemont with a statue of Lenin and the Freemont Troll, a giant concrete troll that has been lurking under the north end of the Aurora bridge and snacking on children and cars since 1990..
The neighborhood we used to live in called Fremont, in Seattle, used to have an annual parade which included naked cyclists but they were covered with body paint, which was tasteful enough that we were comfortable taking my elderly devout Catholic MIL, but in the last few years we attended, starting in about 2011, it had degraded to just naked people parading down the street.
Seattle cops are pussies and refuse to do anything.
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