SR 203 is maintained by the Washington State Department of Transportation (WSDOT), which conducts an annual survey on state highways to measure traffic volume in terms of average annual daily traffic. Average traffic volumes on the highway in 2016 ranged from a minimum of 7,200 vehicles near Fall City to a maximum of 14,000 vehicles north of Duvall. Most of SR 203 is a rural, shoulder-less highway with two lanes and a speed limit of outside of city centers. A short section of the route within Monroe is also designated as a MAP-21 principal arterial route under the National Highway System. Due to the road's low-lying route alongside the Snoqualmie River, it is routinely flooded during winter storms and often closes for several days each year.