> North Dakota's unemployment rate is 2.3%

So? What's your point? During the boom, laborers from all over went to North Dakota to work in the oil fields, and for the unemployment to say low there, most of them had to leave. And, IIRC, North Dakota wisely refused to build too much permanent infrastructure to support that population, because they knew it would be transient. If there was much effect on unemployment statistics, it was probably in other states (though I would guess the effect was more on wages than binary employment).

My point is boom jobs evaporate, and give a recent example.