the use of railroads and commerce is still vital.

In fact, in Kentucky alone, some $40 billion, that's with a B, $40 billion in goods originating here are shipped via rail every year.

But what were once prosperous rail lines 150 or so years ago, oftentimes fall into disrepair and are abandoned.

Some Kentucky communities, though, are looking to repurpose old tracks in a variety of innovative and entertaining ways.

We hit the rails to take a look.

[train honking] In the 1800s, railroads profoundly changed America.

Distances were shrunk, new towns and new industries sprang up, and mass migration to the West was enabled.

In Kentucky, trade that was once exclusive to waterways, like the Ohio River, could now thrive just about anywhere.

But the advent of the automobile meant many once-thriving railroads went under.

That led to many lines being abandoned.

In fact, research shows by the end of the 20th century, more than 100,000 miles of abandoned rail lines were littered across America.

That's where groups like the Rails to Trails Conservancy come in.

They work with community groups to convert abandoned lines into multipurpose trails.

When they first started 40 years ago, around 100 miles of reclaimed rail lines across the country were used as trails.

That number now stands at more than 26,000 miles.

I had a chance to speak with Eric Oberg from the organization's headquarters in Washington, D.C.

The railroads opened this country up.

They were a transportation renaissance.

And the legacy of those railroads are still with us.

And the railroad industry is not a dead industry.

It is a thriving industry still.

But the amount of rail corridor that was built in the heyday of the railroads, there was a lot of redundancies, which gives us the opportunity to reuse so many of these.

And because of the way rail lines were built, they lend themselves perfectly to trails that can be enjoyed by just about anyone.

The engineering that went into building a railroad was amazing, right?

It needed to be fairly flat.

So you've got a maximum 3% grades.

You are either tunneling through mountains or trestling over river valleys to create this flat grade, which makes an unbelievable surface for a trail, right?

The most accessible possible trail there is.

Anybody can use a rail trail.

Oberg says one of the more interesting rail-to-trail conversions in Kentucky is the Dawkins Line Rail Trail, which runs from Johnson County to Breathitt County.

Before it was paved, the trail was popular with horseback riders.

He says eastern Kentucky, in particular, is ripe for this kind of project.

There's really excited exploration happening in coal country in eastern Kentucky.

The National Park Service River Trails Conservation Assistance Program is working with some communities out there, not looking at abandoned rail corridor, but still some active rail corridors, and saying, “Are there opportunities to maybe co-locate rail with trail in some of these eastern Kentucky communities?” So, I mean, there's just a lot happening in Kentucky.

There's so much opportunity for more, though.

One of the highest-profile repurposing projects occurred in Louisville, where the Big Four Railroad Bridge was converted into a pedestrian bridge.

Built in the late 1800s, the bridge was a major carrier of rail freight from Kentucky across the Ohio and to all points north.

The last train crossed it in 1968.

And a few years later, the approaches in Kentucky and Indiana were removed, earning it the nickname, The Bridge to Nowhere.

It sat like this for nearly 40 years, until it was reopened as a part of Louisville's Waterfront Development Project.

The approach is a giant corkscrew that gradually brings pedestrians to the bridge that crosses the Ohio and to Indiana.

In Versailles, part of the old Louisville Southern Railroad there was decommissioned in the 1980s and was converted to use by a rail museum that takes passengers on tours.

But a couple of years ago, a group called Rail Explorers started offering a different type of excursion.

Passengers ride rail bikes where they pedal on a 10-mile round trip through the heart of Versailles and Woodford County, through distilleries and horse farms.

Even though some of the bikes weigh up to 750 pounds, an electric assist motor makes the experience pretty effortless, and you can trust me on that one.

The history of this rail line that we're on right now, what can you tell me about this?

So this rail line was built in the 1800s, and this was the main line to get from Lawrenceburg all the way into the Lexington Train Depot.

I think one of the biggest things that a lot of people don't realize is how active this rail was during its prime time, because we're all so used to car culture now here in Kentucky, that now you can hop on a bus or drive with your friends to get to point A, point B. But for the longest time, if you were in Lawrenceburg in the middle of the 1800s and you needed medicine, food, fuel, whatever, if that doesn't come on a carriage, it's coming on a train.

So if we don't have these lines, a lot of people would have lost out on really the opportunity to grow as a city.

Kentucky owes a lot of its growth to the railroad.

Before the interstate system that connects all of our cities now, a lot of infrastructure and support for these communities, the only way in and out was through rail lines.

So, are a lot of these old rail lines just kind of left to rot?

Do they just sit here until nature takes them over?

Does that happen a lot?

More or less.

If somebody like the museum or us doesn't come in and offer to maintain the track or take it over from the Federal Rail Association or Federal Rail Administration, then at the end of the day, typically, the ties are all removed, and it just becomes a big gravel path through the middle of some forest.

That was the case in Park City, Kentucky, where an eight-mile rail line was constructed in 1886 to connect the small town to a world-renowned tourist attraction.

They were building the L&N Railroad from Louisville to Nashville, of course, for freight and things like that.

So they decided that they would stop here since Bell's Tavern was here, and that was where people stayed.

When they wanted to go to Mammoth Cave, they went by horseback and by stagecoach, and that's how it began.

They figured out they needed another way.

So what they did is they built a hub from the L&N tracks to go to Mammoth Cave, to the visitor center.

When the first car made the trip from Park City to Mammoth Cave in 1904, the popularity of the rail line began to falter.

It was completely abandoned in the 1920s, where it sat lifeless for more than 80 years.

In 2007, the city worked with the National Park Service to construct the Mammoth Cave Railroad Bike and Hike Trail.

It's used for a variety of activities.

We were there on a cold October morning when dozens of runners set out on a 50-kilometer race that traveled the trail.

According to Watts, who's with the Park City Tourism Commission, the investment in converting the old rail line to a trail has paid off and enhanced the livability of the town.

If you look at the old map, in 2007, it didn't say anything about, there was no lodging, no restaurants, nothing.

And we have three restaurants.

One just opened again last week.

And then, we have four B&Bs, and we have the Grand Victorian Inn.

Places that are doing better are concentrating on these quality of life amenities that make people want to live in those places.

And it doesn't matter whether it's a big city, metro area, or a small rural community.

People still want these super high-quality of life amenities, and trails are part of those.

Because no matter what you're doing on a trail, when you pass somebody, whether they are a neighbor, a friend, a family member, or a complete stranger, at the very least, you give somebody a nod.

More often than not, you say hi.

Many times, you're going to stop and have a conversation.

That's community.