Gender of geographical names which are neither city nor country names

Question

How do I determine the gender of geographical names which are neither city nor country names?

I am aware of the following principles for determining the gender of country and city names:

• country names: feminine if it ends in unstressed -a, masculine otherwise [and whether there is exceptionally an obligatory or optional definite article needs to be memorized]
• city names: feminine if it ends in (stressed or unstressed) -a, masculine otherwise (but the feminine gender is also acceptable because one can imagine a preceding "la ciudad de")

What about other geographical entities? Are there patterns they follow? Does the gender generally depend on an implicit or imagined category (eg: "región" f, "barrio" m, "distrito" m)?

Here are some examples:

• states of Mexico: Oaxaca, Tlaxcala
• region: Westfalia (in Germany)
• municipalities in Spain: Almorox, Borox, Guadix, Sax
• parts of cities: Xochimilco (a borough of Mexico City), Mixcoac (area within the Benito Juárez borough of Mexico City)

I also welcome information about simple morphological tests which one can use, eg:

• checking the frequency of: "City Name fue fundado" vs "City Name fue fundada"
• checking the frequency of: "City Name es hermoso" vs "City Name es hermosa" [Would this test have a bias towards the masculine gender because of an imagined "un lugar" before "es"?]

Notes:

• For the Spanish "municipalities", I wasn't sure whether to simply treat them as cities, as I'm not familiar with the system of administrative divisions used in Spain.
• The odd selection of examples stems from me researching the pronunciation of words containing the letters 'h', 'w', or 'x', as these have sometimes exceptional pronunciations. Also I found it difficult to research their gender (as a beginner), due to their somewhat lower frequency.

Answer 1

Proper names designate things or people with a certain gender. Defining the gender is easier with personal names:

• Javier es engreído y Karina es histérica.

As pointed out by OP, the main rules as to the gender of countries and cities can be found here.

However, there is a lot of vacillation, sometimes accounted for by how the speaker "personifies" the place ("Mi Buenos Aires querido" - a famous tango song by Carlos Gardel - and "Misteriosa Buenos Aires" - a fantastic anthology of stories by Manuel Mujica Láinez), but mainly by which common noun is deemed to be the referent of the geographical name.

Danielillo has given an excellent pair of examples:

• (El equipo de) Argentina campeón del mundo.
• (La (Nación/República)) Argentina es la campeona del mundial Qatar 2022.

We can even think of homonymous countries and cities being regarded as masculine and feminine nouns, respectively:

• México (el país) es muy variado en términos de densidad demográfica pero México (la ciudad) es muy populosa.

The names of "estados" will tend to be masculine, the names of "regiones" will tend to be feminine, the names of "provincias" will tend to be feminine, the names of "departamentos" will tend to be masculine, the names of "localidades" will tend to be feminine, the names of "pueblos" will tend to be masculine, the names of "barrios/distritos" will tend to be masculine, because the referents are, as the case may be, masculine or feminine. However, we can always conceive of any of them as "un sitio/lugar", in which case the masculine can be used.