By the year 2000, there were roughly 130,000 rooms in Las Vegas.
By the year 2000, there were about 130,000 rooms in Las Vegas, but most of these were created in a business boom in the 90's. 
mnli hypothesis: By the year 2000, there were about 130,000 rooms in Las Vegas, but most of these were created in a business boom in the 90's.  premise: By the year 2000, there were roughly 130,000 rooms in Las Vegas.