How do I get sidewalks in my neighborhood?

Does anyone know or have experience with getting the county to put sidewalks on their street? Our road is about 3- 4 miles long. I love where I live but the streets are still somewhat rural and curvy and it is really dangerous to walk, although people do. We live in an area where you can only put one house on an acre and I am assuming that there are not alot of people who would want to chip in for something like this and I am sure it is expensive. Any thoughts will be greatly appreciated!