Trade policy? Lets start with some basics here: farms are getting larger, and there is no longer available farm land that wasn't already converted to farm land. That happened a long time ago, before me anyway. Farmer Jo has 4 kids and one farm. That farm only produced enough income for one family to live on, if they are lucky and expanded, maybe two. So Farmer Jo + One kid and family. All the other kids have to go elsewhere. You go look in town (maybe 5000 people in a good healthy farm town), and the jobs there are bleak as well. Cook, mechanic, hardware store, etc. Or you enter the trades: plumber electrician. But in small towns, there is still only so much room for them. These small towns have a form of "max capacity". So most of the kids move way. Out of four, on average 2 kids will stick around, but not enough for the town to "grow". Keep in mind, not every farm kids wants, or is cut out to perform farm labor.
Again, why do the kids leave? The town economy is based on farm economics, and is limited by the availability of land. Once the land is taken, the town will stop growing. And farm income is not what you call "stable" either, so the town goes thru a lot of boom and bust cycles. Infrastructure levies take a hit if you are talking about multiple years of taxes, simply because the farmers don't know what next year's income will look like.
Do you need to flee to the city? Depends on what you call a city. There is probably a neighbor town with +20,000 people in it. We call them cities around here (examples: Twin Falls Idaho and Algona Iowa.) In those vast metropolises you can work produce factories, car dealerships (the small towns don't have them), and other areas.
Source: I'm a farm kid with an older brother, from a small farming town in southern Idaho, and most my friends are former farm kids as well. My dad gave me the "talk" in high school, he knew I wouldn't make a good farmer. And those who stuck around are often not the lucky ones. They are just trying to hold on. (was not a fun heart-to-heart with my brother last night who thinking hard about selling out and becoming an EMT after 30 years of farm life).