(1) Except as otherwise provided in subsections (10) and (11), along interstate highways and freeways, a sign structure located in a business area or unzoned commercial or industrial area shall not be erected or maintained closer than 1,000 feet to another sign structure on the same side of the highway.

    (2) Along primary highways, a sign structure shall not be erected or maintained closer than 500 feet to another sign structure.

    (3) Except as otherwise provided in subsection (4), a sign utilizing a digital billboard permit shall not be closer than 1,750 feet to another sign utilizing a digital billboard permit on either side of the highway facing the same direction of oncoming traffic.

    (4) Beginning on the effective date of the amendatory act that added this subsection and ending 1 year after the effective date of the amendatory act that added this subsection, for the first 8 nonstandard signs for which the owner applies for a digital billboard permit under section 6(6)(a) without having to surrender 3 interim permits as provided under section 6(6)(b), each sign shall not be closer than 1,000 feet to another sign using a digital billboard permit on either side of the highway facing the same direction of traffic. This subsection only applies to signs located in a county having a population of not less than 750,000.

    (5) This section does not apply to signs separated by a building or other visual obstruction in such a manner that only 1 sign located within the spacing distances is visible from the highway at any time, provided that the building or other visual obstruction has not been created for the purpose of visually obstructing either of the signs at issue.

    (6) Along interstate highways and freeways located outside of incorporated municipalities, a sign structure shall not be permitted adjacent to or within 500 feet of an interchange, an intersection at grade, or a safety roadside rest area. The 500 feet shall be measured from the point of beginning or ending of pavement widening at the exit from, or entrance to, the main-traveled way.

    (7) Official signs as described in section 13(1)(a) and on-premises signs shall not be counted and measurements shall not be made from them for purposes of determining compliance with the spacing requirements in this section.

    (8) Except as provided in subsection (3), the spacing requirements in this section apply separately to each side of the highway.

    (9) The spacing requirements in this section shall be measured along the nearest edge of the pavement of the highway between points directly opposite each sign.

    (10) A sign that was erected in compliance with the spacing requirements of this section that were in effect at the time when the sign was erected, but that does not comply with the spacing requirements of this section after March 23, 1999, is not unlawful under section 22.

    (11) Along an interstate highway that is designated by 1 letter and 3 numbers and located in a county with a population of less than 211,000 but more than 175,000, an existing sign structure that was erected prior to March 24, 2011 shall not be closer than 900 feet to another sign structure on the same side of the highway.

    (12) Nothing in this section shall be construed to cause a sign that was legally erected prior to March 23, 1999 to be defined as a nonconforming sign.