The grade of the East Fork of Issaquah Creek ascends rapidly eastward until at High Point the creek is no longer rushing along the bottom of a narrow gorge, but wandering through a wide, flat -bottomed , swampy valley , in which the stream appears incongruously small and ineffective. Two miles east of High Point, this old floor suddenly ends at 540 feet above sea level, with the valley at full width. There is a descent here of about 100 feet to Raging River, which comes in from the southeast and turns northward at this point toward Fall City,

The first wagon road between Issaquah and Preston was constructed in 1887. Known as King County Road #186, or the O.P. Stephenson Road, this early route began in Issaquah at the present-day intersection of W. Sunset Way and Newport Way NW. Here, it connected to the Gilman Road, built in 1864, which ran from Lake Sammamish south to the coal mines on Issaquah Creek, about three-quarters of a mile south of Sunset Way.

From Issaquah, Road #186 followed Issaquah Creek up to Highpoint, though any traces of this section were later erased by the construction of Interstate 90. At Highpoint, the old road continues along what is now SE Highpoint Way. After reaching the top of the hill, it veered northeast, joining what is now called 300th Ave SE, and followed the base of the hill to the north side of the Preston Cemetery. Today, the section between the cemetery and the point where 300th Ave SE turns south no longer exists.

After passing the north end of the cemetery, the road began its steep descent into Lower Preston. A remaining fragment of this road is located below the old railroad grade, where it meets the Preston-Fall City Road, a little over a quarter-mile north of Lower Preston. Here, it once crossed the Raging River via a long-lost bridge and continued up Icy Creek for about a quarter-mile before ascending a very steep incline with over a 20% grade.

Upon reaching the top, the road ran east, south of Lake Alice, to meet the old King County Road No. 7, which served as the Snoqualmie Pass Road. This road then descended into the town of Snoqualmie. In 1889, however, the segment between the Raging River and Snoqualmie Ridge was abandoned due to the challenges of navigating the steep grade. At that time, King County Road #205, also known as the H. H. Ludvigson Road, was constructed from the intersection of Upper Preston Rd SE and the Preston-Fall City Road, becoming the first road to connect Preston and Fall City.

In 1912, construction began on a new road between Tibbetts Creek and Fall City, which would eventually become the Sunset Highway. Starting at Tibbetts Creek, the new road initially used existing roads (now known as Newport Way) and then turned south after rounding the hill to just north of Holly Street. From there, a new section was built to connect with Road #186. This existing stretch of Road #186 was then used for the next two miles, where a new concrete bridge was built over Issaquah Creek. From that point to Fall City, a completely new road was constructed.

Between Tibbetts Creek and Highpoint a total of four concrete bridges were built in 1912, three of which still stand today. The first bridge, located over Tibbetts Creek near where Newport Way meets the Renton-Issaquah Road, was built at an ancient crossing used by the "Na-qui-a-ka Trail," which historically connected Fall City and Renton.

The other three bridges crossed Issaquah Creek between Issaquah and Highpoint. The second concrete bridge can still be seen just east of Issaquah, on the right side of the freeway when traveling eastbound. This bridge is easier to spot in winter when the leaves have fallen. The third bridge, about a mile west of the Highpoint exit, was removed during freeway construction. The final bridge is located east of the Highpoint exit at the end of Lovegren Road.

In 1935, work began on the final improvements to the Sunset Highway between Issaquah and Preston, resulting in the new road that now forms the eastbound lanes of Interstate 90.