Now in its 28th year, the National Pike Steam, Gas and Horse Association's annual show has a lot going for it.

Not only is it billed as "the largest digging show in the U.S.A.," it also showcases working, rather than display, machinery of yesteryear. If the weather is hot, it has lots of shade under its more than 100 acres of wooded terrain.

This year's showcase of puffing, steaming and chugging contraptions, scheduled for Friday through next Sunday, promises to be even bigger when the association hosts the annual convention and show of the Historical Construction Equipment Association.

"We're hoping for as many as 5,000 attendees and have booked hotel rooms from Washington to Uniontown," said Erma McMaster, co-chairwoman of the event with her husband, Louis, and Robert Kelly. "Last year, the HCEA convention in Colchester, Conn., drew about 7,000 visitors."

The show, which will be held off Route 40 in Malden, about four miles west of Brownsville, is open to the public and has such wide appeal that people are expected from as far away as California and Sweden. One construction association member, David Geis, is bringing his tractor and scraper from Seward, Neb.

Joining close to 40 gas and diesel shovels working in what amounts to a giant sandbox are two steam shovels -- a 1927 Erie B and a 1913 shovel built by Thew Automatic Shovel Co. that is not only the oldest in the show but also may be the last in existence.

The Thew, owned by Mr. Kelly, of McDonald, has quite a history. Mr. Kelly bought it in May 1999 from its original home in Jerseyville, Ontario, but when he tried to have it transported to the United States, Canadian customs authorities turned back his driver, who had a truck full of tools, because they believed he might be taking jobs away from Canadian citizens.

Mr. Kelly and his tractor/trailer made it into Canada, but he was worried about getting the shovel back across the border. To assist with potential roadblocks, he contacted a Canadian friend who owned a trucking service with border-crossing privileges. The plan worked, and the Thew eventually made it back to McDonald, where the Kelly family restored it.

The steam shovel made another long trip in 2006 -- to the nation's capital for the 100th anniversary of the Clark Construction Group. A police escort led it through town to a site across from the Washington, D.C., convention center, where it was on display with round-the-clock security.

At next weekend's show, Mr. Kelly also will display his 1927 Byers Bearcat ditcher and a 1926 Keystone skimmer, used mainly for tearing up old macadam roads. A retired heavy equipment operator for Consol Coal Co., now Consol Energy, Mr. Kelly started collecting construction equipment in the late 1950s and has at least 60 pieces.

"Years ago, you could purchase things fairly cheaply," he said. "Nowadays, there's a lot more interest in this equipment and a lot of shows around the country."

In addition to the gigantic construction machinery, the National Pike Association will fire up its own collection of antique machinery, and visitors will be able to see an operating rock crusher, a sawmill, antique tractors and trucks and more.

Youngsters will be entertained with hay rides, pedal-powered tractor pulls, daily parades and a sand pit with toy construction machinery.

On Saturday, a bus tour to Fallingwater and Kentuck Knob will leave the show grounds at 9 a.m. and return about 4 p.m. Cost is $65. On Saturday evening, a buffet catered by the Springhouse of Eighty-Four will top off the convention and show at the Richeyville Fire Department social hall. The cost is $25 per person. Both events are open to the public, and reservations must be made in advance by calling 724-356-2307.

"This will be the third time we've hosted the HCEA convention," Mrs. McMaster said. "They liked our site so much in 1993 and '99, they asked us to host them again this year. Like dummies, we said yes. It's a heck of a lot of work, but it's also a good way to meet up with old friends you usually see only once a year."

The 28th Annual National Pike Steam, Gas and Horse Association Show will be held from 9 a.m. to 7 p.m. Friday, Saturdayand next Sundayjust off Route 40 in Malden, four miles west of Brownsville. Admission is $5. Children younger than 12 admitted free. Senior admission is $3 on Friday. For more information, visit www.nationalpike.com.