My relatives in and near Cody Wyoming, would probably be toast, literally.
I think they'd have time for a short prayer if they were awake. Maybe.
I'm in NW North Dakota, which puts me a few mountain ranges away form the caldera. With that in mind, if it happened tomorrow, in daylight. Shockwave effects: I think we'd hear the initial eruption, maybe not, but the mountains in between would block most of the shock wave.
My reckoning is that we'd see the plume go up, have a few hours before the ash started falling, and I expect we'd have to bug out to the NE to get out from under that plume. Another effect, though, could be far more significant. I'd expect with the warm air generated by a caldera eruption, and looking at past ash distributions from eruptions, that a high pressure system from the arctic would be coming in from the North, muy pronto.
I'd expect winter temperatures to drop 30-60 degrees, and in summer, I think temps could get to -20. In short, part of any bug out from the region should include winter gear. (twenty to thirty below is a normal winter temp range here, I have seen -60, not counting wind chill).
I'd expect an accumulation of up to 2 feet of ash where I live, and staying would mean sealing windows and shoveling roofs to keep structures from collapsing.
Long term effects: The year without a summer. Obliteration of all crops in the ashfall area on the hoof, and possible destruction of stored grain in elevators and bins. Livestock in the open would not fare well, and even protected livestock would have pulmonary issues in short order. Select breeding stock to build a new herd from scratch--even they are going to be hard to feed for a year or two, and butcher and preserve the rest, as best you can. Any disruption of electrical power could lead to spoilage of massive quantities of butchered meat.
Long term, the ash would be sterile in terms of the soil bacteria which are normally helpful to plant growth. Any accumulations thicker than normal plow depth would have the effect of sterilizing the soil, and that may impede agricultural recovery.
Wildlife in the region would do poorly, and some species might be completely wiped out in the region.
Oil production facilities in the region, from North Dakota to Texas would be negatively impacted. Most are not designed for an additional two to four feet of material falling out of the sky, but prompt action could maintain most production, but transportation, distribution, and refinery facilities might be severely impeded at any but the pipeline level. Much oil in pipelines is gathered via tanker truck, so eventually disruption of roads would lead to a serious reduction in fuel supplies.
Rail travel would be severely impacted as tracks were buried, same with roads, and the ash would clog air filters on any internal Combustion engine. They would have to be removed and replaced or cleaned in order to keep engines running. Open water supplies (reservoirs, rivers) would be laden with sediment, depending on how close to the caldera and in which part of the plume. The Platte, the Yellowstone, and parts of the Missouri would be very turbid, eventually, the Mississippi. This may negatively impact water supplies in many midwestern towns.
Most humans are only a few meals and a paycheck away from incivility. Reams could be written on the effects on human behaviour, but it would be what is commonly described as a SHTF scenario, on top of the effects of the natural disaster.
And there is the nice rosy picture. There is a reason they call such events disasters.
