We are trying to determine if this is an ant or a beetle:
The insect pictured is in fact a beetle in the family Cerambycidae. It appears to belong to the New World genus Euderces, many members of which are known to mimic ants. This particular species is probably Euderces pini, the double-banded ant-mimicking cerambycid.
You can learn more about ant mimicry by checking out this previous post, and more specific examples of ant mimics here, here, here and here. This last link discusses ant mimicry (or perceived ant mimicry) in two other species of cerambycid beetles found in the U.S.
Thanks for your interest!
Alexandra Westrich & the AntAsk Team