A right-of-way (aka "R-O-W" or just "ROW") is a stretch of land that has been put aside for a future roadway, trail, etc. We often refer to the "Rt. 135/Seaford-Oyster Bay Right-of-Way" or the "Bethpage Parkway Right-of-Way." In both cases, we are referring to land that had been purchased by NY State to accommodate the original routes of these roadways, but was never used.
Today, the State still owns much of this land and has not done anything with it. In my neighborhood, the old Rt. 135 R-O-W exists as a series of wooded lots at the ends of several residential streets. Some residents clean them up occasionally, but others just dump their old mattresses and refrigerators there. A linear park with the Bethpage Bikeway Extension running through it would have cleaned all that up and turned over responsibility for cleaning to NY State.
On another note: On Friday, I noticed a new green "info" sign for the bikeway planted on Southwoods Rd. It's got a historical photo of the Syosset LIRR station (c. 1912) that I paid a collector $25 for back in the mid-1990's and then used in my book about the community. I suppose the DOT got hold of a copy through the Syosset Library, which then shamelessly gave it away without insisting on a proper credit for me. Bummer. I coulda been immortalized on a bike path!