Back in the 1980's at the fairgrounds in the San Bernadino area of LA they used to have a huge gun show. LA does not allow city/county owed facilities to be used for gun shows nowdays so I imagine gun shows in that area are gone forever.
I left LA in 1993 so I have no idea what goes on down there today.
Portland, OR had a pretty large show at the Expo Center put on by Rose City Gun Collectors. Its in process this weekend.