We're self-sustaining primarily through property taxes and have been that way for more than a century.
From the tone of other commenters here, I sense a malicious undercurrent intent on extinguishing rural ways of life - any excuse will suffice.
Like how the residents of New York City are able to get the food and water it needs all produced within the five boroughs? Or is that a different kind of "subsidy" from the hinterlands.
It's nonsensical to say that just because the tax receipts of a suburb doesn't pay in full its roads and bridges, its existence is necessarily subsidized by the rest. Does a city pay in full for its share of the US Navy whose protection of global commerce it depends on to survive? Are cities subsidized by the blood of those in the armed forces, who primarily come from the hinterlands?
Yet.
"In every region of the country, recruitment rates were higher in rural and exurban counties than in urban counties. Only urban counties in the South had recruitment rates above the national average. Cities in the Northeast, Midwest and West all had rates well below the national average." [1]
[1] https://dailyyonder.com/largest-share-army-recruits-come-rur...
Or were you planning on creating isolated servants in rural area who only work all day and never go anywhere?
The free market will sort it out in short order.