A photo in an article with a caption that reads:
Law enforcement officers during a raid of a gambling house in the 1940s. At upper left is Mike Elliott, whose campaign for Multnomah County sheriff would be financed by gambling racketeers. (Oregonian archive)
(source)
Why is it "at upper left"? I thought it is idiomatic to use the preposition on and with the definite article, "on the upper left". Is at upper left correct?
Unfortunately, preposition usage is tricky. My first thought was
In the upper left is Mike Elliott...
However, any of in, on, or at seem acceptable to me in this example. For example, it's possible to say at the left, at the top, etc. I believe the definite article is required in typical speech and writing, just as you suspected. In other words, at the upper left sounds better to me than at upper left. I think the reason the author omitted the definite article was due to headlinese:
Forms of the verb "to be" and articles (a, an, the) are usually omitted.
Notice that the first "sentence" is also in headlinese.
When it comes to a plain page with clear corners especially on the web, at is also used. That's why you may hear 'at the bottom of the page,' 'at the left corner,' and so on.
The definite article is not used because it merely tells the direction and not the place. That said: '...at upper left is Mike...' but '...at the upper left corner, there is Mike...'
