The Rails-to-Trails Conservancy has been "greenbanking" thousands of miles of America by creating trails from abandoned railway tracks.

The group envisions a system of trails ribboning across the country, according to an article in the current issue of Country Living, creating a labyrinth of slim, linear parklands or "greenways" connecting metropolitan areas, rural communities, local parks and a wide range of ecosys-tems.The endless spiderweb of railroad tracks that crisscrosses the country once represented its economic backbone.

As the end of the 20th century approaches, railroads are finding it difficult to compete with trucking, personal automobiles and commercial airlines. The result is more specialized routes and the increasingly frequent abandonment of railway lines and corridors.

It is these abandonments that have led to the popularity of the Rails-to-Trails Conservancy.

Started in the mid-1960s as a loosely knit grass-roots initiative in the Midwest, the rail-to-trails movement has blossomed into a national nonprofit organization.

It was founded in 1985 by lawyer David Burwell and a group of environmentalists and cyclists. The group, which boasts some 62,000 members, works in partnership with citizens' groups, public agencies and the railroads.

With railroad companies surrendering the rights to more than 3,000 miles of track a year - about half of the 300,000 miles of track in operation in the '20s has already been abandoned - the Conservancy is kept quite busy.

At this time, 279 trails beckon hikers and naturalists and the organization is working with more than 350 municipalities to acquire new parklands in their hometowns or counties. There are 3,187 miles of these greenways operating across the country.

Virginia's Washington and Old Dominion Railroad Trail, the country's most heavily used rail-trail, stretches 44 miles from the Potomac River to near the Blue Ridge Mountains.

In Washington State, the 23-mile Burke-Gilman Trail, the second most heavily traveled trail, is used for recreational purposes as well as a nonmotorized commuting thoroughfare for Seattle residents.

In southwestern Ohio, the 45-mile Little Miami Trail delights cyclists, hikers, daydreamers and naturalists.

In the East, the 20-mile Cape Cod Trail meanders between Dennis and Eastham, Mass., traveling alongside ponds, ocean beaches and quaint New England villages.

Southerners head to Florida's capital to explore the incredibly scenic Tallahassee-St. Marks Trail, while Californians have their pick of 28 scenic greenways, including the Bizz Johnson, the longest in the state, and the Ojai Valley Trail, with its parallel treadways for horses and bike riders.

California ties Pennsylvania for the most converted corridors, but Wisconsin takes first prize for actual trail miles - 510. Michigan ranks second in miles with 369.

Converting rails to trails is not an easy job. While the Conservancy's expertise is invaluable to communities wishing to convert an abandoned railroad corridor, actual labor is normally undertaken by either a state or county park system.

Altercations occur over titles to the railroad land and over misgivings homeowners with adjoining property frequently express. One common fear is that increasing pedestrian traffic will lead to higher incidence of crime.