When the Maryland State Roads Commission applied numbers to state highways, they assigned MD 170 to its current corridor from Severn to Brooklyn Park and to what is now MD 174 from Severn to Fort Meade. The portion of the modern highway from Odenton to Severn was originally MD 554.
When the Maryland State Roads Commission assigned numbers to state highways, they designated MD 170 to its current route from Severn to Brooklyn Park and MD 174 to the stretch from Severn to Fort Meade. The segment of the modern highway from Odenton to Severn was initially designated as MD 554.