Is the International Building Code accepted nationwide?

Here is some information about building code in general.

The International Building Code (IBC) is divided into many smaller sub codes covering in more detail the various technical and various disciplines involved in building. We are primarily concerned with the IBC as well as the International Residential Code for One- and Two-Family Dwellings (IRC). Adoption of codes is done on a local level. The localities can be states, counties, or cities; in any case it is the local building department that has jurisdiction. Some localities have adopted clauses to the international codes to address specific concerns in their areas. For example, some areas only allow a power fan to be rated by its hole size (Net Free Area) because of eventual motor burn out. Others eliminate soffit vents above windows and doors because of condensation and fire concerns. Most building codes are the same when it comes to attic ventilation requirements.