There is always a great unknown in going back to a racetrack that once was popular and then fell from grace until it finally vanished from the schedule.

IndyCar tried Phoenix, a bastion of open-wheel racing for four decades that used to have two races a year and pack the place, from 2016-2018 and it was a box office flop. Now it’s gone again, likely to never return.

Loudon drew 50,000 in 1995 before falling into the crevice created by The Split and it was a ghost town five years later. When IndyCar gave it another shot in 2011, it was a well-kept secret that fizzled and was instantly filed away under one and done.

Watkins Glen never drew very well whether it was CART, IRL or IndyCar and the plug got pulled after 2017 but, to be fair, it’s never had a decent date and could probably be draw a reasonable crowd it ran in June with IMSA’s six-hour race.

Gateway started off with a big crowd in 1996 before gradually losing any kind of a following and it was gone by 2004. When Curtis Francois brought it back in 2017, everybody cringed because the odds were so long but thanks to Francois’ drive, the relentless promotion from Chris Blair and John Bisci and the best title sponsor to come along in a decade in Bommarito Automotive Group, it was a hit and backed it up again a couple weeks ago.

When IndyCar announced it was returning to Portland the immediate reaction was more skepticism than optimism because of the way it had ended in 2007 under Champ Car.

After being one of Oregon’s major sports attractions from 1984 to 2000 on the strength of the Rose Festival and sponsors like GI Joe’s and Budweiser, interest dwindled just like attendance and it looked to be another chapter of Where Are they Now?

But what we saw last Sunday can only be called a renaissance in the Pacific Northwest that was both super encouraging and successful. There were great crowds for three days and something we hadn’t seen (except for Indianapolis) in years — traffic jams getting into the track at 8 in the morning along with big lines of people waiting to buy tickets.

They came from Seattle, Vancouver, Eugene, Spokane, Boise, Medford, Northern and Southern California and Portland. They got there early and stayed late.

More importantly, they were real IndyCar fans. They wore hats and shirts from the good old days as well as current swag and they knew Spencer Pigot and Gabby Chaves from Josef Newgarden and Tony Kanaan. It was like being at Road America or Mid-Ohio or Gateway.

And here’s the kicker: They spent the whole weekend thanking the drivers and teams for coming back. “I’ve never had so many people say thank you and I kept saying, ‘No, thank you for coming,’’’ said Newgarden.

Promoters Kevin Savoree and Kim Green added Portland to go with St. Pete, Toronto and Mid-Ohio but were warned early and often about their date.

“We were told that Labor Day was terrible because everybody leaves town,” said Savoree. “And I’ll admit that kinda scared me but then our ticket sales weren’t showing that and we got more and more confident it could work.

“And I can’t say it any plainer: this weekend was fantastic.”

Considering Savoree and Green had no title sponsor (almost certain death to any promoter nowadays) to bang the drum, the fact there were an estimated 40,000 at Portland International Raceway was nothing short of miraculous.

Savoree said they could have sold out the campers’ lot two or three times and the walk-up seemed to match the ticket sales in terms of volume.

As mentioned, Portland drew massive crowds in CART’s heyday as did Vancouver and people have been writing to RACER’s Mailbag for the past several years saying that the Pacific Northwest was starving for Indy cars.

They got a bellyfull over the weekend but I get the feeling they’ll be back for seconds in 2019.