From the news:
NASA is hosting a series of events on the National Mall.
The National Mall is a national park, and we usually use the preposition in:
The events in the national park were magnificent.
Here are some numbers from nytimes.com:
"on the National Mall" site:nytimes.com 1290 results
"in the National Mall" site:nytimes.com 3 results
Why doesn't the National Mall take the preposition "in" like other national parks? And what does it mean to have "on" for the National Mall?
The National Mall may be a park, but it is also a mall (3rd definition):
A shady public walk or promenade.
The preposition choice used in a sentence does not usually have to do with what the object is in reality (or the various groups to which it belongs) but rather what it is being called in the phrase. If NASA said they were hosting events in the Washington Mall National Park, the preposition would fit - but if one is hosting on a mall, then one hosts on it, as one cannot host in a shady walk. A park, being a described area, has events held in it, while physical landmarks without enclosures, such as malls or hills, have events held on them.
As another example, consider someone who holds a picnic on Mount Rainier versus someone who holds one in Mount Rainier National Park. One would be quite unlikely to hold a picnic in a mountain, regardless of whether the mountain has been designated as a national park.
