Globe Swift pilot reported safely landing on a road after experiencing engine vibration and loss of power. The power loss was later traced to carburetor ice.

Narrative

I was flying southbound from ZZZ to ZZZ1 at 3500 feet MSL when I started to notice engine vibration. As soon as this happened I started looking for the closest airport to land at. I began my deviation while losing power and altitude. Over the past few months we had been dealing with vibrations with the engine. We changed the engine mounts and after that did not alleviate the issue we tried to balance the propeller. We ended up buying a new propeller and that corrected the issue. While flying this time; I started noticing a similar vibration. I did not think of carb heat as the reason why I was developing the loss of power. I was well above the RPMs where I thought carb ice would be an issue so in my mind I thought of other reasons as to why my engine was quitting. I focused my attention entirely to the fact that I may have lost a cylinder and I considered my options. At this time I was too low to make the airport and the fact is that I would have had to clear a windmill farm to get to airport that I was deviating to. I was also approaching a windmill farm in front of me. All these circumstances; along with the high surface winds and gusts created an urgency in my mind to get the airplane safely to the ground while there was still time. This is the point where I decided to land on a road that was between to farms. I let ATC know my intentions; I requested priority handling and landed the airplane safely and with partial power. I turned the engine off. Made sure that there were no anomalies like oil in the cowling or anything else. Everything looked normal. A couple hours went by and I turned the engine back on; carried out a run up and noticed everything was normal. It turns out carb ice was the culprit.