Maryland Route 121
State highway in Montgomery County, Maryland, United States, known as Clarksburg Rd
Maryland Route 121 (MD 121) is a state highway in the U.S. state of Maryland. Known as Clarksburg Road, the highway runs 3.96 miles (6.37 km) from MD 117 in Boyds north to Stringtown Road between Interstate 270 (I-270) and MD 355 in Clarksburg. MD 121 connects Boyds and Clarksburg in northern Montgomery County. The highway was paved from Clarksburg to Boyds in the early to mid-1910s. MD 121 was extended to north of Clarksburg in the late 1920s and early 1930s. MD 121 was relocated through Clarksburg in the mid-1950s when I-270 was constructed through the area. The highway's northern end was rolled back to MD 355 in the mid-1970s. MD 121 was relocated in Boyds in the mid-1980s. The highway's northern end was moved to its present terminus just north of I-270 when Stringtown Road was constructed in the mid-2000s. In addition to the Boyds–Clarksburg route, MD 121 has also included three disjoint segments in Dawsonville and Germantown.
Begin with the source’s own compact description: “Maryland Route 121” is state highway in Montgomery County, Maryland, United States, known as Clarksburg Rd. The dossier treats that line as a proposition to test through Maryland, Route and State, not as a finished interpretation.
Why this record matters
The phrase “state highway in Montgomery County, Maryland, United States, known as Clarksburg Rd” supplies a clear boundary for inquiry. It also exposes the unanswered questions: who defined that boundary, when it became stable and which sources sit outside it.
The strongest evidence will usually combine a dated visual record with documents produced by the authority responsible for the place. The source revision retrieved here is dated Apr 19, 2026. The linked authority identifier is Q2448641.
Modern boundaries and familiar names can conceal earlier jurisdictions or structures that do not align with the present site. The lead is largely declarative, so disagreement and counter-evidence require a deliberate search beyond the opening account. Authority statements aid reconciliation but still require their own references, qualifiers and ranks to be checked.
How to read it
Treat names, boundaries and functions as historically changeable. Maps, plans, inventories and administrative records can clarify what the place meant at different dates.
- Historic place names
- Jurisdictional context
- Routes into maps and plans
Contemporary maps, plans, listed-building records, estate papers and the responsible local or national archive.
Three-step research path
- Establish the record: confirm the title “Maryland Route 121”, its source revision and the description used here.
- Expand the search: follow Maryland Route 121 primary sources, Maryland Route 121 archive and Maryland research across catalogues and specialist indexes.
- Test the account: compare the strongest cited source with the responsible institution’s current record and note any disagreement.
Questions for further research
- Which source most directly establishes the central claim about “Maryland Route 121”?
- What physical evidence or contemporary plan supports the description?
- Which authority defined the place, boundary or structure at the relevant date?
Search terms from this dossier
This entry incorporates text from “Maryland Route 121” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.