From wikipedia. I guess its just badly written and 'shortly after' means a decade

"The Tropicana Atlantic City officially opened on November 23, 1981 with 521 guest rooms and casino space. Shortly after opening a unique indoor amusement area called Tivoli Pier was built and within a year the name of the resort was changed to TropWorld Casino and Entertainment Resort."

Then again, your NY Times article is hardly accurate either. "A decade after". What decade? It was in the same decade. Sounds like a spanish mile Do you have those in the US?