When I was a skydiver (1981 - 2004), USPA membership was required to
jump at any USPA affiliated skydiving center, which was practically all
of them. When I started taking gliding lessons at one of the largest
schools in the country I was astonished to learn that not a single
staff member was an SSA member.

I've since come to understand how and why SSA doesn't enjoy a
similar situation, but it still surprises me how many active pilots in
the USA do not maintain SSA membership.

~ted/2NO