Don't be surprised, he says, if you get the "willies big-time. I've had perfectly normal people tell me that they have stood in the sandstone scar over Deep Rut Trail in Wyoming or in the trench over California Hill in Nebraska and simply trembled with emotion."

A second reason for the guide, however, is equally important, he says — to encourage preservation. "When a person has read that history, stood right on those pioneer pathways and driven or hiked the pioneer routes, it is unlikely that there will be much support for proposals which would damage or destroy the historic trails or sites."

Yet a lot of the trail has been lost — or at least paved over or built on. And that's one reason Franzwa got into the "trail business" more than 40 years ago.

Born in Iowa, a veteran of World War II, a journalism graduate from the University of Iowa, he has always been interested in history. He moved to St. Louis in the early 1960s, and his first book told the story of Ste. Genevieve, a historic French settlement along the Mississippi River.

"I was delivering some of my books to the bookstore at the Gateway Arch and happened to see another book on the rack. It was Francis Parkman's 'The Oregon Trail.' It has been in print since 1848, and I asked the book manager how it was doing all these years later. He said, 'compared to yours, about 100 to 1.' So I bought it to read. Parkman was a snooty young grad student when he wrote it, but it's an awfully good book."

Captivated by what he read, Franzwa rented a trailer and followed the trail "as far as we could go. We got to Casper. We checked out a hundred books on the Oregon Trail, and no one could tell us exactly where it was. I came back and started my own research."

That led to a number of guidebooks and map books on the Oregon Trail. Then he was hired by the National Park Service to do a series on the Santa Fe Trail. But, he says, "I was never as hot on the Santa Fe trail." For the most part, it was carved by freighters and teamsters, whereas the Oregon Trail was etched by ordinary folks looking for a new life.

But as he was working on those books, he realized that a lot of people "were not paying attention to the trail. They were plowing it up, grading it away. I found 12 people who were still interested, and we met in Denver in August 1982 and founded the Oregon California Trail Association. Last year, I gave the keynote address at the 25th anniversary meeting. There are now some 1,700 members."

It was through that association that he met Kimball, who had done a lot of research on the Mormon Trail, "and we remained friends ever since."