Hreflang for regions (like states and provinces) within a country

Question

I'm working on a website which has different content depending on the province/state the user is from.

Is it valid to add the subdivision code to the hreflang like below?

<link rel="alternate" hreflang="en-ca-ab" href="https://www.example.com/ca/ab/example/"/> 

If not, is there another way to let search engines know that the content is specific to a certain province/state?

Answer 1

In short, no. The "Supported language/region codes" section of Google's hreflang guidelines is fairly unambiguous:

The value of the hreflang attribute identifies the language (in ISO 639-1 format) and optionally the region (in ISO 3166-1 Alpha 2 format) of an alternate URL.

The use of the word "region" there is perhaps confusing. ISO 3166-1 Alpha 2 codes denote countries¹.

What you probably want to do is known as local SEO, which relies more on content and off-site optimisations to target search queries with local intent. It's beyond the scope of your question to cover that here.

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¹ To be really pedantic, even this is semantically troublesome. For instance, the constituent countries of the UK don't have their own codes, even though they are countries (not states or provinces).

Answer 2

The HTML5 specification defines hreflang like this:

The hreflang attribute on a elements that create hyperlinks, if present, gives the language of the linked resource. It is purely advisory. The value must be a valid BCP 47 language tag. [BCP47] User agents must not consider this attribute authoritative — upon fetching the resource, user agents must use only language information associated with the resource to determine its language, not metadata included in the link to the resource.

(see https://www.w3.org/TR/html5/links.html#attr-hyperlink-hreflang)

BCP47 is IETF document "Tags for Identifying Languages". It details how a language tag is formed and its possible content.

The parsing is basically language[-script][-region]*("-" variant)*("-" extension):

1. the first part is the language as defined in ISO 639-1 Alpha-2 codes, so en from your case, with optional extended language subtags,
2. the script is 4 characters, so not your case here (it is optional),
3. the region is from ISO 3166-1, country codes, and it is preferred to be in uppercase, hence CA,
4. variant subtags are defined as used to indicate additional, well-recognized variations that define a language or its dialects that are not covered by other available subtags. but they are at least 4 characters (see point 4 of 2.2.5)

So en-ca-ab does not seem valid to me. The ISO 3166-2 code for Alberta in Canada is "CA-AB", but you can not use it as a variant as is (because of its hyphen and because each variant is registered in a registry).

In fact if you input your string at http://unicode.org/cldr/utility/languageid.jsp you will see it is labeled as invalid. I also see no registration for "Alberta" in https://www.iana.org/assignments/language-subtag-registry/language-subtag-registry

In short, do you really think/need to define the English Canadian language as spoken in Alberta because it is so different from English Canadian, which would be the valid en-CA language tag?

Remember that you are identifying a language, not a geography. If you want to specify that part of your website is related only to this specific province (for example if you provide services only there), then it is not a language issue, and hence should have nothing to do with hreflang.

Answer 3

In terms of hreflang you can't specify your content more detailedly as with the schema of language and country.

I would however highly recommend to make use of structured data, specially https://schema.org/audience and https://schema.org/spatialCoverage. With both properties you are able to communicate the covered region very exactly.

The question, which remains for me without an answer, is: how do you technically deliver different content to different regions? IP-based? Is it working enough precisely for you?