This isn't necessarily the case with my situation. There was only one hospital for where I lived in Marquette, Michigan. My mental healthcare was pertaining to gender dysphoria and not depression which I think you're associating with longer winters. Anyway place I grew up was filled with religious nuts to make things short. They forcibly prescribed me with antipsychotics while ignoring my right & modern medical approach of gender dysphoria. Montreal is a large city compared to that place and is progressive like California. So basically where you're located when it comes to social structure is huge.

I think small rural town versus major metro center has more to do with the quality than US vs Canada.

It’s no different in Canada - small towns don’t offer as good of care particularly when it’s something that’s not common.

I think I might have heard this at some point in the past.

Anyway, I found a reference to support your claim:

Also consistent with the conclusions of Torrey1 and Saha et al,2 our analyses shown in table 3 found a strong tendency for prevalence to increase with latitude.[1]

1. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2669590/

I'm not aware from the article of how the illness "schizophrenia" foreshadows all of mental health. My illness being Gender Dysphoria.

Vitamin D deficiency from what I've read is common everywhere. It does make sense that longer winters would impact a person such as staying inside more. Yet I doubt any evidence can confirm lack of Vitamin D is associated with the illness schizophrenia.

Ah, yeah, that's a good point. Schizophrenia is probably a poor proxy for all mental illness.

And there's probably at least quite a few things that aren't mental illness that benefit from mental healthcare.