I just finished the series the and I'm a little confused as to why Hawkins's bomb was need to convince Texas to side with the US. They already had an intact bomb recovered from the failed attack on NYC.
---
Committed Brony
We don't know much about what has happened and what is happening in the East other than that the remnants of the old government are banded together. Any number of fates could have befallen the bomb since the attacks. It's not necessarily explained what happened to the New York bomb but through David Reynolds we can safely assume that the NYC bomb is not available to our protagonists.
Lots of options Could be that it was destroyed, secretly recovered by J&R, or that the U.S. government in the East has it and has already dispelled the J&R myth in the East, but that Hawkins was necessary to bring Texas into the fold. It makes sense that we wouldn't hear about what happened to that bomb since Jericho was pretty good at only letting the audience learn what the characters learn, and no one ever had a lot of information about the other government.
Or it could have been something they were keeping for a future storyline that sadly never got to see fruition.
---
"Pride is not the opposite of shame, but its source. True humility is the antidote to shame."