Originally Posted by fxdave
Bob what exactly does that mean ? we were looking to go in a few weeks i heard the weather comes quick but what is shutting down plse explain thanks bob also then when is a good time to to do this trip ?
They start closing facilities in the park starting with things at higher elevations and then the closings flow through the park about every week.
Yellowstone National Park - Facilities' Opening & Closing Dates (U.S. National Park Service)
By the end of September many of the stores, lodges and CG's will be closed. By mid October most of them will be closed. The park roads will most likely be open, depending on weather, but you could get hit by heavy snow anytime after mid September. RV parks and stores outside the park start closing down in mid September.
That said, Fall is a great time to visit if the facilities are not important to you.
My opinion is that September just after labor day is great because traffic is way down, or starting on about May 15th for spring.