We rode this trail on 9/12/20, starting at the parking lot on route 63.
Overall, a nice trail, but it has a lot of plusses but also some things that could be considered “minuses” by some.
Plus:
Shaded, pretty sections high over the adjoining forest.
Some nice scenery including horse farms (and horses share the trail, we passed several), plus several ponds. Route goes through the woods the whole way…very little in the way of passes through suburbia.
Not crowded.
Not a huge number of road crossings, and typically with good sight lines.
No big hills, some gradual ups and downs.
Minuses:
Most of the train is hard packed dirt or stone dust that makes for a good surface. However, there are significant sections that are a bit rougher. Some of the road crossings involve a downhill, cross the road, and then an uphill…often with a lot of stone or sand involved. There is a section around mile 8-9(when going West) where the trail follows something like a creek bed, with large stones that make it problematic (we walked this section). There are some embedded stones along the way so you have to watch where you’re going and steer around them..or even walk briefly. Some sections do have some drainage issues, so just need to be careful there. And parts of the trail become more like singletrack. We were able to navigate the entire route with our mountain/trail bikes (30 or 32 cc tires)…I would not recommend a conventional skinny tire road bike here.
Please don’t think the minuses outnumber the plusses here. Overall I recommend this trail because it’s pretty and ridable. Maps are available at the Connecticut DEP website.
Finally I recommend starting at the Naugatuck route 63 parking area…several other posters have noted that there’s basically no parking if you start in Southbury.
Check out the Air Line trail and the Hop River trail, not too far away in central Connecticut, for other options you may want to try.

Took the family and it was very clean and an excellent time. Windy and lots of hills and downhill runs. Recommended

This was a lovely, but popular walk. The only issue is that all but one small car park has been closed to non-local residents due to COVID. So unless you have a parking permit, you’ll need to head to Palace Street where there are a small number of metered parking spaces.

First & most important: start in Naugatuck !! Zero parking in Southbury. Don’t be put off off super steep hill - it’s only about 80 yards - just wheel your bike up to the top & you’ll be on nice flat rail bed. First time ride this trail. Had a raw unfinished feel to it. Some steep up & downs at road crossings which were little off putting outbound but on return was expecting them & didn’t even have to dismount for 3 out of 4 of them. One section like riding a dry river bed - take it slow or walk - only 200 yards or so. Sone areas muddy and would be messy after rain. Despite unfinished feel was well maintained and even huge fallen trees had been cleared. Very peaceful ride. I have hybrid bike regular tyres not fat ones.

easy, beautiful, peaceful, friendly, shaded Great for walking and biking

We started in Bridgeport in the park near the zoo, but I would recommend going from Tait Road onwards because it’s a proper trail from there onwards. From Bridgeport north to that point is nice but more road noise and you need to cut through some neighbourhoods to connect up w the other parts of the trail. We had a lovely day out though. Hilly in places but not too hard.

The process of approving and paving the Old Putnam Trail is finally complete. While the trail isn't officially open, it's accessible from Van Cortlandt Park. Due to a recent storm, there are numerous downed trees; however, there are worn paths to get around them. You just have to get off your bike a few times. While the trail was fun to ride even when it was rough, the new surface is very smooth, really quick, and accessible to all. This trail provides access from the Bronx to Westchester County, via the South County and North County trails.

As of 08/12/2020, this trail was closed off by the roundabout on Bethpage State Parkway. I believe this is due to the damage caused by Storm Isaias.
if anyone has been to the trail recently please update the status on the condition.
much appreciate.

Pretty quick, simple and easy trail. Beautiful scenary in between. Yes CT 15 adds some noise but not unbearable. Rabbits and butterflies all along.