For the past few months, it's been coming together piece by piece, slowly becoming something that people in Newburyport are aware of and appreciate.

By next spring, it will no doubt become a major asset to an already foot- and bike-friendly city.

The Clipper City Rail Trail is not yet finished, but even on these cold and gray November days, it is drawing a loyal following. Most of it is now paved, and bicyclists and walkers can be found on it just about all the time. Their numbers grow a little every day.

One can only imagine the flurry of activity it will see when the warm rays of the sun greet us next spring. By then, the trail will be just about finished.

Rail trails have been growing in popularity for years now, and they are clearly a good use of long-abandoned railroad lines — especially when they link interesting destinations. Newburyport's rail trail links the commuter rail station with the waterfront, and it has several well-planned access points along the way that allow people to get onto High Street, Low Street, Washington Street, Merrimac Street and the waterfront.

Meanwhile, an equally impressive companion rail trail is nearly complete. The Salisbury Old Eastern Marsh Trail follows the same railroad right-of-way that the Clipper City trail runs along, but will provide a dramatically different viewing experience. It passes through the extensive salt marshes that meander along the north bank of the Merrimack River. It connects Salisbury Square to downtown Newburyport.

In the long term, the Salisbury trail will be greatly extended. It will follow a long-abandoned railroad spur line that once connected Amesbury's bustling carriage factories to the main rail line. When this section of the rail trail is completed, it will nearly link up with Amesbury's Riverwalk — which also follows along a portion of that spur line.

In the not-too-distant future, it will be possible to ride a bicycle from downtown Amesbury to downtown Newburyport — about five miles or so — almost entirely on rail trails. That's pretty impressive.

Newburyport will someday have a second rail trail, which will follow an old spur line that once connected the downtown coal docks to the main line. It will run through the eastern and southern ends of the city, eventually looping into the waterfront park. The city's downtown will literally be embraced by rail trails and harbor walks.

These trails are well worth your time to check out. They are yet another reason why this region is so attractive.