In any case, methinks your obsession with unemployment rate is one of the things that we must seriously reconsider if we really want to be objective about the merits (or lack thereof) of basic income (BI).
Let's get a bit philosophical here. One of the fundamental premises of BI is that it's OK for a substantial portion of a future society not to do anything that is traditionally considered "work". And one of the reasons we need to experiment with BI is to see whether or not this seemingly outrageous premise turns out to be correct after all.
Including the unemployment rate in your definition of "it can work in the U.S." is inherently biased against BI because it already assumes the opposite of one of the premises of BI. It's like trying to decide between theism and atheism using the Bible as your measuring stick. Regardless of what conclusion you draw at the end of the day, that competition ain't fair.
In order to make a fair decision, we'll need to go a little meta and ask, for example, about the total productivity of the society, the physical and mental well-being of its citizens, or something like that.