Recipient's Address at Top or Bottom

I have noticed in some letters - particularly, by government officials - that the address of the recipient is written at the end of the letter (i.e. beneath the signature, justified to the left). Two examples of this are at the following links:

- https://www.cnn.com/2016/12/23/politics/trump-putin-christmas-letter-russian-relations/index.html

- https://twitter.com/teddyboylocsin/status/1267786798731628545/photo/1

Why is this the case? Does this reflect an established letter format that is not mentioned on the internet?