In the early-to-mid 1970's, the city would close off the slope of Ross Ave with cones, and direct the DPW to not plow or salt the street. This was for local kids to do sledding. There was enough side streets reach Ross Ave, for local homeowners to park their cars on the street and walk to their houses, and those were thoroughly plowed. Poplar and Euclid were plowed, it was only Ross that was for sledding.
There would be dozens of kids at a time, from all over the Fairmount Section, sledding on Ross Ave. I moved to Hackensack in 1973, and sledding down Ross Ave was a tradition at that time. I can't remember when this stopped, but I'd say by 1976 or 1977 it was over, and they started plowing and salting. Most kids had wood sleds with metal rails; I think the plastic ones were something just coming out, and mostly for really young kids. The plastic ones were slower and safer.
Also the back of the old Borg house was a popular sledding area, and even now it is occasionally used. There was sledding down several hillside trails in the woods that have since overgrown. Especially one that used to line up with the trail that crossed the back of the swamp area. That was a steep drop from the wooded bluff, behind the house with the circle driveway and tulip garden. Actually that hillside was the property of that house, since sold to Bergen County to be included in the woods preserve.