“Over” versus “More Than.” As an editor, I come across this all the time in writers’ articles. It’s one of those things — kind of like when people mistakenly use “that” instead of “who” when referring to people (Writing Tip #66) — that often gets by even the most discerning editorial eye.
Usually, Grammar Girl is my go-to source for this kind of stuff, but in this case, I don’t agree with her rationale. As I wrote in her comments, the way I learned it is that you use “more than” when you’re talking about something that cannot be broken down beyond whole numbers, such as “more than 700 people.” However, you CAN say, “over $12 million” or “over 12 percent.” Both dollars and percentages can be broken down further to cents and percentage points. The actual figure might be $12.3 million (and a few cents) or 12.6 percent, after all. However, when it comes to 700 people — or oranges or waffles or canisters of Scotch tape — you can’t have 700.7 of them, and that’s why “more than” is the correct choice and not “over.” “Over” implies you can break that number down further.
But after reading the Grammar Girl post and its assorted comments, I realized that what I had thought was a grammar “rule” is not necessarily one. There is apparently no definitive say on the matter. However, I’m going to stick to my guns — all “more than (fill in the blank)” of them. :)