If you are at the stage where you are looking for land, try and set up a meeting with the local planner if there is one, and tell them what you want to do, and why. An hour of this persons time can save you thousands of dollars of mistakes and give you real concrete ideas about what it takes to do real estate development in your area. Don't be discouraged if it seems impossibly expensive and epic. You are continuing to discover it's going to take commitment to do this. Rezoning States and Counties regulate land use through zoning.
Land is grouped together that has similar uses and characteristics.
Often zoning issues in urban areas are defined by some sort of master development plan. Understanding the master plan will help you evaluate your rezone prospects. Some areas, especially rural ones, have very lax rules about how many homes you can place on an acre, and other such requirements. Other areas have very stringent requirements and running afoul of these can cause you endless problems. There is a usually a process for changing the zoning of a particular piece of land.