The annual Winnebago Itasca Travelers (WIT) Grand National Rally (GNR) opened Sunday (July 15) and runs through July 20 at Winnebago Industries Inc.’s rally grounds in Forest City, Iowa,  according to a report by the Mason City Globe Gazette.

Kelli Harms, public relations specialist, said about 1,000 units had registered as of the end of June.

Some units started arriving over the weekend but many volunteers came earlier to help prepare the rally grounds.

“We have people who come as early as July 1,” Harms said.

Early arrivals stay busy in the region and many volunteer.

“WIT Club counts on many volunteers to prepare the rally and (to work) throughout the rally,” said Denise Yeager of Winnebago Industries and the WIT GNR.

Volunteers help get units parked, put up street signs on the rally grounds, teach classes and do other tasks for the GNR. Attendees can also participate in pre-rally events this week, Harms said.

A trip to the Mall of America in Bloomington, Minn., a tour of historical architecture in North Iowa, and a bike ride to Pilot Knob State Park are just some of the events planned for this week, Harms said.

The theme of this year’s GNR is “Treasure Island.”

“We have a number of new activities and events this year-like a real treasure hunt,” WIT General Manager Doug Formanek said in a news release.

This year also marks the first year towable recreational vehicles are allowed on the grounds. Winnebago bought SunnyBrook RV, a towable manufacturer, in 2010. The company is also making Winnebago brand towables.