The 16th Street Limited Line, designated Route S9, is a limited stop MetroExtra bus route operated by the Washington Metropolitan Area Transit Authority between Silver Spring station, which is served by the Red Line of the Washington Metro, and McPherson Square station, which is served by the Orange, Blue, and Silver lines of the Washington Metro. The line operates every 5–10 minutes during rush hours, 15 minutes during weekday midday and Saturday and 20 minutes on Sunday. Trips are roughly 40–50 minutes long. This line provides additional service between Monday and Saturday along the 16th Street corridor supplementing routes S1 and S2.