So I know what I want to have happen I just don't have a plausible "why". Its typical young adult distopian stuff, set in the usa, in the future. They've mostly run out of gas, there's no power for cars and such so long distance travel is next to nonexistent. Most people have moved out of cities and started their own farms but people in smaller towns still manage. Also, cell towers, radio towers, satellites, and phone lines have been slowly falling into disrepair since no one can get out to them to fix anymore, thus communication has mostly reverted back to pen and paper mail, short wave radio, local internet servers within towns and the occasional access to satellite communication if they are lucky. Essentially, the government needs to be invading its own states under the guise of another country, silently wiping out entire cities with chemical weapons and then disappearing. No one is aware of this because of the limited communication. The story is going to focus on one particular group of people in Oregon or Washington state who were warned in advance by a government "traitor" and evacuated their town. But now I'm stuck. I don't have a good reason for why the government is doing this. Initially, I had considered something to do with shale reserves and fracking, perhaps the govt needed the oil but the people were opposed to it so they killed them all to get the resources (or some big company paid the govt)... But there's no big underground oil reserves in OR/WA so that's out. I could do something with other natural resources like timber or farmland but it doesn't seem to fit to kill people in cities for that... I could also do something with the Cascadia movement, say OR, WA, and BC were trying to break away from the USA and Canada respectively and the central govt were opposed to that but I'm not sure how I would frame that, nor what would trigger them to split off but make the govt want to keep them... Any ideas or just general comments on the plausibility of it all would be great. Also, if this sounds really cliched and overdone please be very blunt and tell me. Thank you!
A rebel group in those cities rallying the cities to get away from the US because of how bad they're handling the situation. The US is trying to feed all these people because they're obligated to but they can't so they kill off a lot of people to make it easier for them. Check out the show Revolution that just ended on NBC. They didn't renew it but I thought it was pretty good. Pretty much, one day the power goes out and it doesn't come back. 15 years later, after the US collapses and new governments form, the US comes back (they evacuated to Guantanimo Bay for whatever reason). First they forced the Monroe Republic and Georgia Federation to nuke each other when the power turns on for 15 minutes for whatever reason, then they fake an attack on a town in Texas and they annex that. They then try to make Texas Republic and California Federation go to war so they can reclaim the lost land. It's worth watching and it's similar. The main character is a 19 year old girl so it can relate.
If you're going the dystopian route, then there's nothing wrong with flat out twisted ideology. Having a group of elitist claim that wiping out all of the "cancerous" people who caused the disaster in the first place (scapegoating) is in the best interest of the whole is completely acceptable. Look at New World order conspiracies and stuff like that for more specific examples. There's already a built in audience for stuff like that too.
The fracking reason seems like a good one. You can say, here be a new hitherto undiscovered gas resource and go with it. You're setting it in future right? So there can be a say, newer technology that has found new deposits. I'd guess gas running out would put further impetus to such research. And your idea seems mighty interesting, people reverting back to older forms of communications and such.
Hmm kinda reminds me of the Ashes series, although it's a bit different to what you are insinuating. Anyway it could still be a good way in to the story. In the series the leader (Ben Raines) splits away from the government after nuclear strikes and the world is almost destroyed. He ends up creating his own country within America; where peace, equality and good working stand. Anyway back to my point, you could have a pre history check where you explain that a group of people tried to take control by forming their own government. When they saw what was happening to the country; they ended up getting wiped out. However there were a few that escaped and the government is hunting them down ( used as a cover story). (Info on the series I was on about) http://tcrane.tripod.com/johnstn.html
Similar to what another poster said, they are doing this to simply "clean" the country of poverty. Naturally, in such circumstances, garbage will be accumulating, sicknesses won't be treated etc, and these will be most prevalent in the poorer areas where lots have gathered to try and live (not those who have their own farms, since they are in a way contributing by raising animals, feeding themselves and occasionally others etc and the government sees them as potentially beneficial to the future). It could be as simply as that - they want to clean up and a war is a perfect disguise. OR, going on something another poster said about rebels, there could be a rebel group that is growing. Since the government can't figure out who is who, they just go to the cities or areas where there are suspected rebel groups and kill everyone, pretending that they are invading from another country as a cover. These rebels could perhaps be building their own society or technologies, and the US gov doesn't want to lose their power so they resort to a fake invasion.