At first they were considered a toy. Introduced in 1969 by Honda, all-terrain vehicles came with three fat tires, an engine and bikelike handlebars. A decade later they would be used more for commercial reasons, such as farming, as opposed to recreation.

Today's models have four fat tires, an engine, albeit somewhat more powerful, and bike-like handlebars ... along with self starters, winches, high-tech suspension, cargo racks and even GPS capabilities.

And they definitely fit into the recreational vehicle category.

They are easy to start, easy to ride, can comfortably carry two and, here in Utah, there are hundreds of riding opportunities available. The evolution into today's machines started when it was discovered that the early three-wheel models were deemed dangerous after a rash of injuries and deaths. So in 1985 manufacturers started to add a fourth wheel to stabilize the machines.

The addition of the fourth wheel has made ATVs safer, more versatile and easier to ride. All of which have combined to fuel the growing popularity.

A survey taken between 1997 and 2001 showed:

• The number of drivers rose 36 percent from 12 to 16.3 million.

• The number of driving hours rose 50 percent from 1,575 to 2,364 million.

• The number of ATVs rose 40 percent from 4.0 to 5.6 million.

Today, according to the Specialty Vehicle Institute of America, it is estimated that roughly 16 million people will use the nearly 7 million ATVs in service in the United States, which is up sharply from the estimated 3 million in use back in the 1980s.

Here in Utah there are 152,841 registered off-highway vehicles, which far surpases the 28,221 registered snowmobiles.

Back East, in states such as Wisconsin, snowmobiles were once the ruling recreational vehicle, now ATVs are. Latest figures in Wisconsin show there are 298,678 registered ATVs compared to 214,758 registered snowmobiles.

It is a fairly common sight here in Utah these days to see a pickup bed loaded with an ATV or a trailer in tow with one or more ATVs onboard, headed for off-highway trails somewhere within the state's boundaries.

At many sites, where ATVs were once a rarity, they are now commonplace.

Scott McFarland, owner of Highpoint Hummer & ATV Tours in Moab, said interest has been building there for about five years.

"A lot of the ATV owners are coming from Salt Lake and Denver areas. There are so many places to ride, finding somewhere to go is not a problem," he noted.

One of Highpoint's more popular rides is called 7-Mile Rim, which is located between Canyonlands and Arches national parks.