MD 97 crosses the Patuxent River into Howard County, where it becomes Roxbury Mills Road, named after the Roxbury Mill built in 1753.
It continues north, passing areas of woods and farms along with suburban residential developments.
 The road heads through the community of Glenwood and continues through agricultural areas before intersecting MD 144 (Frederick Road) in the community of Cooksville.
A park and ride lot is located at the northeast corner of this intersection.
A short distance later, the route has an interchange with I-70/US 40.
Past this interchange, MD 97 becomes Hoods Mill Road and passes rural residential areas, intersecting Old Frederick Road.
From here, the road winds through a mix of woods, farm fields, and residences before crossing the South Branch of the Patapsco River.

Upon crossing the river, MD 97 enters Carroll County and becomes Old Washington Road.
 The road crosses CSX's Old Main Line Subdivision railroad line as it passes wooded areas with some residences.
It runs through a mix of woods and farms with some residences along the road.
The number of residences increases as the route crosses Streaker Road in Berrett.
From here, MD 97 passes more residences before intersecting MD 850 (Old Liberty Road) at a roundabout.
A park and ride lot is located northwest of this roundabout.
A short distance later, the route intersects MD 26 (Liberty Road) at a folded diamond interchange in Dorsey Crossroads.
Past MD 26, MD 97 becomes New Washington Road and heads north through a mix of farmland, woodland, and residential neighborhoods, paralleled to the west by MD 854 (Old Washington Road).
The road passes through woodland before intersecting Nicodemus Road, where it continues past farms and woods before heading west of a park and ride lot and crossing MD 32 (Sykesville Road) in Fenby.

Past this intersection, MD 97 passes to the east of Carroll Community College and heads into residential areas as it approaches Westminster, bypassing the center of the town to the east.
 The route becomes Malcolm Drive past the intersection with Main Street/Old Westminster Road and continues to an intersection with MD 140 (Baltimore Boulevard).
Here, MD 97 makes a left turn to form a concurrency with MD 140 on Baltimore Boulevard, a six-lane divided highway.
The two routes head through commercial areas on the outskirts of Westminster, passing by the TownMall of Westminster before meeting MD 27 (Manchester Road) at a folded-diamond interchange.
Past this interchange, the road passes over the Maryland Midland Railway and heads past more businesses.
At the Sullivan Road intersection, the road becomes College View Boulevard and a short distance later, MD 97 splits from MD 140 at an interchange near McDaniel College.

MD 97 continues north on Littlestown Pike, a two-lane undivided road.
The road passes east of the Carroll County Regional Airport before heading into a mix of farmland and residences.
MD 97 intersects the southern terminus of MD 496 (Bachmans Valley Road), and continues northwest through agricultural and wooded areas with intermittent residences.
It passes through Union Mills, where the road intersects Old Hanover Road.
MD 97 continues to the community of Silver Run, where it passes residences.
Upon leaving this community, the route continues through woods and farm fields.
A short distance later, MD 97 reaches the Pennsylvania border, where the road becomes PA 97 and continues north into Adams County.
MD 97 crosses the Patuxent River into Howard County, where it becomes Roxbury Mills Road, named after the Roxbury Mill built in 1753. It continues north, passing areas of woods and farms along with suburban residential developments.  The road heads through the community of Glenwood and continues through agricultural areas before intersecting MD 144 (Frederick Road) in the community of Cooksville. A park and ride lot is located at the northeast corner of this intersection. A short distance later, the route has an interchange with I-70/US 40. Past this interchange, MD 97 becomes Hoods Mill Road and passes rural residential areas, intersecting Old Frederick Road. From here, the road winds through a mix of woods, farm fields, and residences before crossing the South Branch of the Patapsco River.
Upon crossing the river, MD 97 enters Carroll County and becomes Old Washington Road.  The road crosses CSX's Old Main Line Subdivision railroad line as it passes wooded areas with some residences. It runs through a mix of woods and farms with some residences along the road. The number of residences increases as the route crosses Streaker Road in Berrett. From here, MD 97 passes more residences before intersecting MD 850 (Old Liberty Road) at a roundabout. A park and ride lot is located northwest of this roundabout. A short distance later, the route intersects MD 26 (Liberty Road) at a folded diamond interchange in Dorsey Crossroads. Past MD 26, MD 97 becomes New Washington Road and heads north through a mix of farmland, woodland, and residential neighborhoods, paralleled to the west by MD 854 (Old Washington Road). The road passes through woodland before intersecting Nicodemus Road, where it continues past farms and woods before heading west of a park and ride lot and crossing MD 32 (Sykesville Road) in Fenby.
Past this intersection, MD 97 passes to the east of Carroll Community College and heads into residential areas as it approaches Westminster, bypassing the center of the town to the east.  The route becomes Malcolm Drive past the intersection with Main Street/Old Westminster Road and continues to an intersection with MD 140 (Baltimore Boulevard). Here, MD 97 makes a left turn to form a concurrency with MD 140 on Baltimore Boulevard, a six-lane divided highway. The two routes head through commercial areas on the outskirts of Westminster, passing by the TownMall of Westminster before meeting MD 27 (Manchester Road) at a folded-diamond interchange. Past this interchange, the road passes over the Maryland Midland Railway and heads past more businesses. At the Sullivan Road intersection, the road becomes College View Boulevard and a short distance later, MD 97 splits from MD 140 at an interchange near McDaniel College.
MD 97 continues north on Littlestown Pike, a two-lane undivided road. The road passes east of the Carroll County Regional Airport before heading into a mix of farmland and residences. MD 97 intersects the southern terminus of MD 496 (Bachmans Valley Road), and continues northwest through agricultural and wooded areas with intermittent residences. It passes through Union Mills, where the road intersects Old Hanover Road. MD 97 continues to the community of Silver Run, where it passes residences. Upon leaving this community, the route continues through woods and farm fields. A short distance later, MD 97 reaches the Pennsylvania border, where the road becomes PA 97 and continues north into Adams County.
Maryland Route 97