The female dancers are really for experts, not for a European

. I suspect that the two last pictures are female Vivid Dancers. The California D. and the Aztec Dancer have a more narrow line on top of thorax (in front of wing base).
The first one is teneral male with soft wings etc. I can just see the secondary genitalia below 2. abdominal segment, indicating a male. The spikes on the legs are long compared to the distance between them, indicating a Dancer (Argia) and not Bluet (Enallagma). It might be possible to idenify it based on the dominant white band on the thorax.
Erland