No sign shall, subject to the provisions of Section 23-1-274, be erected or maintained in an adjacent area after February 10, 1972, nor shall any outdoor advertising sign, display, or device with the purpose of its message being read from the main-traveled way of an interstate highway or primary highway be erected after April 11, 1978, outside of an urban area beyond 660 feet of the nearest edge of right-of-way of an interstate or primary highway, except the following:

(1) Directional and official signs, including, but not limited to, signs pertaining to natural wonders, scenic and historical attractions, safety rest areas, and information centers, which are authorized by the director, under promulgated rule, and which comply with regulations promulgated by the director relative to their lighting, size, number, spacing, and other such requirements as may be appropriate to implement this division; provided, that such regulations shall not be inconsistent with, nor more restrictive than, such national standards as may be promulgated from time to time by the Secretary of Transportation of the United States pursuant to subsection (c) of Section 131, of Title 23, United States Code.

(2) Signs lawfully in existence on October 22, 1965, determined by the state, subject to the concurrence of the United States Secretary of Transportation, to be landmark signs, including signs on farm structures or natural surfaces of historic or artistic significance, the preservation of which would be consistent with the purposes of this section.

(3) Signs advertising the sale or lease of property upon which they are located.

(4) Signs advertising activities conducted on the property on which they are located. For the purposes of this subdivision, the promotion of activities at other locations or the dissemination of information about activities conducted upon other property shall not be considered activities conducted on the property on which a sign is located.

(5) Signs located in business areas on February 10, 1972, and signs to be erected in business areas subsequent to February 10, 1972, which when erected, will comply with the provisions of Section 23-1-274; provided, that no advertising, sign, display, or device with the purpose of its message being read from the main-traveled way shall be erected after April 11, 1978, outside an urban area beyond 660 feet of the edge of the right-of-way of an interstate or primary highway, whether located in a business area or not.

(6) Signs or devices which advertise or designate exclusively the location of the facilities of any public utility located along the interstate or primary highway for the convenience or protection of the using public or the protection of the facilities of the public utility.

(7) Motorist directional signs lawfully erected and in existence on May 5, 1976, which do not conform to requirements of present state laws and whose removal would work a substantial economic hardship in a specific or defined area. The State Department of Transportation, upon receipt of a petition, declaration, or resolution from any state, county, or municipal agency, from any industry association or any group of private business persons or their employees, claiming that the removal of such motorist directional signs would work a substantial economic hardship in specific or defined areas, shall forward such petition, declaration, or resolution to the United States Secretary of Transportation to approve retention of such motorist directional signs.