As a circular highway, M-185 has no specific termini; the generally accepted starting point is at the mile 0 marker placed in front of the Mackinac Island State Park Visitor Center.

[7][9] No part of M-185 has been listed on the National Highway System,[10] a network of roadways important to the country's economy, defense, and mobility.

[17] In 2008, USA Today named the island one of the "10 great places to get your feet back on the ground" as a car-free destination, highlighting the unique status of M-185 in the process.

[19] The trip around the island "provides a photo opportunity at every bend in the path", according to the PSA Journal, the official magazine of the Photographic Society of America.

[21] From its starting point, M-185 heads east between Marquette Park, at the base of Fort Mackinac, and the marina at Haldimand Bay.

[7][21][22] After rounding Mission Point, M-185 continues north-northwesterly along the eastern shore of Mackinac Island, first passing Dwightwood Spring then the Arch Rock viewing area just beyond the mile 1 marker.

The next two miles (3.2 km) of M-185 are relatively isolated and devoid of major landmarks as the highway rounds Hennepin Point and runs along Voyageur's Bay.

The area is a popular stopping point for tourists biking or walking M-185; it is the location where British troops came ashore during the Battle of Mackinac Island during the War of 1812.

Other than a few newer residential developments, the sights are limited to Brown's Brook, which features a picnic area and interpretive nature trail, and the views of the Mackinac Bridge as the trunkline rounds both Heriot and Perrot points.

[24] Visible to the east of the hotel is Michigan's second Governor's Mansion, which is used as a summer retreat for the state's chief executive.

M-185 through downtown Mackinac Island passes through the major business district, featuring dozens of shops, restaurants and lodging establishments; nearly a dozen of these outlets feature the authentic Mackinac Island fudge made fresh daily during tourist season.

[7][21][22] The first city ordinances banning all motorized vehicles from the island were passed on July 6, 1898, with similar state park rules coming in 1901.

[25] The residents complained after a doctor's car scared their horses and caused carriage accidents, and these complaints prompted the ban.

With the cessation of the car ferries across the Straits of Mackinac, and the extra costs to get the necessary equipment to the island, annual maintenance rose to $14,000/year (equivalent to $111,000/year in 2023[31]).

A 1901 Geneva steam-powered car toured the island and was exhibited in Marquette Park before being towed by horse back to British Landing.

The land adjacent to the highway on the east side of the island is publicly owned while along the west it is mostly private.

The panels were created in a collaboration between the Little Traverse Bay Bands of Odawa Indians and the MISPC along with funding by Mackinac Associates, a friends group that works with the state park.

[41] In late 2019, high water levels and winter storms damaged sections of the highway, and MDOT initiated emergency repairs including some erosion mitigation measures at a projected cost of $350,000.

M-185 was closed at the state park boundary north of the Mission Point Resort to British Landing, a distance of about four miles (6.4 km) in mid-June.

This project includes the installation of rip-rap to help protect the roadway from rising water levels in the Great Lakes.

Additionally to accommodate tourists, the roadway will be initially rebuilt with a gravel surface to be paved later in the year as work progresses.