When is it appropriate to use the article the in geographical names? Some types of terms are consistent, but for other categories, usage differs depending on the type of name. The following discussion lists categorical examples and explains why the is used with some designations and not others.
Geopolitical names usually do not require an article: Names of thoroughfares rarely, if ever, have one: “First Avenue” and “Main Street,” for example, are not preceded by the, and though Broadway as a name for a thoroughfare used to be styled “the Broadway,” this usage is long extinct. However, highways and other major concourses often have a descriptive name such as “the Pacific Coast Highway,” and though numbered routes do not require an article, many people in (or from) Southern California will refer, for example, to “the I-5” rather than simply I-5 as an abbreviation for “Interstate 5.” (This usage is apparently customary in Ontario, Canada, as well, and the British refer to their highways as “the A-1” and so on.)
Names of municipalities, with one significant exception—The Hague, in the Netherlands—do not require an article, though names of countries sometimes include the, as in the example earlier in this sentence and in “the Philippines,” when the nation’s appellation describes a number of areas or islands. (However, note that with the peculiar exception of “The Hague,” the article is never capitalized in such usage.)
Individual islands do not include the in their names (except in descriptive designations such as “the Big Island” for the island of Hawaii as distinct from the collection of islands of which it is the largest), but names of islands generally include the article as in “the Philippines” (or, sometimes, “the Philippine Islands”); some names always include or exclude the geographical term (“the Channel Islands,” but “the Hebrides”). The is not used before names of continents, however, though it is employed in reference to parts of landmasses such as in “the Arabian Peninsula”). In naming larger, areas, too, the is employed, as in “the West” and “the Middle East”; the same is true of designations of points on the globe, such “the South Pole” and “the Equator.”
Names of rivers, gulfs, seas, and oceans always include the, but, oddly, those of creeks and lakes do not, except for the latter in descriptive names like “the Great Salt Lake” or collective designations such as “the Great Lakes.” (Descriptive names of watercourses such as “Sandy Creek” do not follow this rule.) Names of bays vary in usage: Both “San Francisco Bay” and “the San Francisco Bay” are heard, for example, and though including the is the exception rather than the rule, it is integral in such names as “the Bay of Biscay” where the geographical term comes first.
Mountains generally do not have the in their names, except in such descriptive cases as “the Matterhorn” or in reference to mountain ranges (“the Rocky Mountains” or “the Rockies,” “the Andes”). Names of features such as deserts and forests, however, almost always follow the in American usage (such as “the Allegheny National Forest”), though in the United Kingdom, in references to forests and woods, the article is omitted (as in “Sherwood Forest”).