According to the U.S. Patent and Trademark Office filing, "Silver Strike" (as we collectors think of it) was first used on December 1, 1992. Global Gaming Distributors filed the trademark in December of 1993, though that application wasn't made public until May 1995. I suspect that Bally's used it in 1994 (since that's the date on the glass) without knowing that Global (which was acquired by Anchor Gaming in March 1994) had already filed for a trademark on it, though they should have recognized that there would be a potential conflict. My guess is that Anchor told Bally's to cease and desist using "Silver Strike" in 1995 when the trademark was issued, since trademark owners must protect their marks to maintain the validity of their registration. Anchor was later bought by IGT, which now owns the mark. BTW, there's a good but somewhat dated history of Anchor at http://www.answers.com/topic/anchor-gaming.

Here's the Silver Strike listing from the Patent and Trademark Office:

Typed Drawing

--------------------------------------------------------------------------------
Word Mark SILVER STRIKE
Goods and Services IC 009. US 026. G & S: currency and/or credit operated slot machines and currency and/or credit operated games of chance which dispense prizes. FIRST USE: 19921201. FIRST USE IN COMMERCE: 19921201
Mark Drawing Code (1) TYPED DRAWING
Design Search Code
Serial Number 74471009
Filing Date December 15, 1993
Current Filing Basis 1A
Original Filing Basis 1A
Published for Opposition May 30, 1995
Registration Number 1913061
Registration Date August 22, 1995
Owner (REGISTRANT) Global Gaming Distributors, Inc. CORPORATION NEVADA 3127 Industria Road Las Vegas NEVADA 89109
(LAST LISTED OWNER) IGT CORPORATION NEVADA 9295 PROTOTYPE DRIVE RENO NEVADA 895218986

Assignment Recorded ASSIGNMENT RECORDED
Attorney of Record SANA HAKIM
Type of Mark TRADEMARK
Register PRINCIPAL
Affidavit Text SECT 15. SECT 8 (6-YR). SECTION 8(10-YR) 20051209.
Renewal 1ST RENEWAL 20051209
Live/Dead Indicator LIVE