Tropo ducting is very rare here. The weather elements needed for the ducting occurs often in the Midwest and East Coast. Due to the dry climate here, the duct usually ends in Kansas before it gets here. The enhanced path to Nebraska was probably one of the rare cases of ducting.
What happens here far more often is E layer skip. This is when the E layer of the ionosphere becomes ionized and becomes an efficient reflector on frequencies up into upper VHF. This usually occurs in spring and fall when the sunspot numbers are approaching their peaks. Solar flares are often followed by E-layer enhancement. We are now at the bottom or at the beginning of the 11 year solar activity cycle and sunspots are at a minimum.(Also known as solar minimum.) In a few years, E-layer skip will be a common occurrence. For now, it will be extremely sporadic.
I have personally seen television from Canada on channels 3 and 4 in an active spring. Low band channels from the east coast appear on an almost daily basis. Boston fire's low band VHF channel ( around 46Mhz, memory escapes me and it is off the air now anyway) was used as beacon and predictor of what may be coming on higher frequencies.
On 6 meters, when I first started, I had more countries (11) confirmed than I did states (4).