Difference between "run into", "come upon" and "come across"

Question

These phrasal verbs have a similar meaning (please correct me if not):

• run into
• come across
• come upon

Are there any nuances to choose between them? For example, I might be wrong but I mostly see run into used for meeting a person unexpectedly.

Update: My understanding of responses so far:

• come upon is not very common any more
• run into is the most frequently used one
• run into might or might not have a negative connotation (No consensus as I see it)

Perhaps working on some concrete sentences might give a better result. For example, which one would you use for (in parentheses are my first thoughts):

• Unexpectedly meeting a dangerously fierce pack of dogs on the street (run into)
• Unexpectedly meeting a very beautiful girl whom you don't know on the street (come across)
• Unexpectedly finding a book that you had lost (come across)
• Unexpectedly finding a grammar mistake in a blog that you'd love to point out (come across)
• ...

Maybe I should've mentioned stumble upon too. By the way, sorry about the length of the post. I had to expand it to clarify the context.

Answer 1

In my experinece you run into people and trouble:

I ran into Betty at the store today. I haven't seen her since college!
I ran into your co-worker Bob today.
Sorry I'm late; I ran into heavy traffic.

You come across objects:

I was cleaning up the kitchen and came across that phone bill you lost.
I was looking up (something) in the encylopedia and came across this interesting tidbit.

I'm not sure I'd use either when talking about a grammar error in a blog; I'd be more likely to say I found or noticed it. I don't know why that is.

Answer 2

When you run into something, it's likely to be metaphorical and those metaphorical encounters are usually negative. The most common noun collocates are: problem, trouble, wall, difficulty, opposition, resistance, and roadblock. It also commonly means meeting a person unexpectedly.

The next item, come upon, is far less common than run into and is usually used when have physically moved into a situation or location. The most common noun collocates are: scene, sight, and accident. And the most common adverbs are suddenly and finally, which are almost equally frequent, suggesting this is used both when you're searching and when you're not.

About as frequent as come upon is come across, the most common meaning of which is that you've physically travelled across something (e.g., a bridge), and there's also the meaning of how you are perceived (i.e., come across as), but in the sense suggested by this group of finding vocabulary, usually it's something your find while reading. Relevant collocations are: article, reference, and script.

Answer 3

They all mean "to encounter unexpectedly", but are used in different contexts:

• Run into means to encounter someone (or something) during your normal course of events, often while physically traveling: I ran into Sally at the supermarket.

• Come across means to find something (or someone) when you were not looking for him/her/it: I was cleaning out the garage when I came across my high school yearbook.

Note that the phrase "come across" has a completely different sense where it also means "to be understood (perhaps wrongly)": I tried to tell her I was worried about her, but I'm afraid I came across as critical instead of concerned.

• Come upon means to find a thing or (often) a situation during your course of events, somewhat similar to "run into" except usually referring to inanimate things or situations and without the implicit subcontext of physical travel: While reading Paradise Lost , I came upon the most amazing literary passage. It's often used interchangeably with "come across" (the first sense).

I disagree that "come upon" is now uncommon. It's never been an overly common expression, but I think it's probably used as much now as ever.

Answer 4

The distinctions are very subtle, and while I don't necessarily disagree with Brett, I think he's overstating. To really answer this you might need to study many examples in context.

I think that "run into" tends to be used to describe something you find accidentally when travelling. (Not necessarily to a foreign country or anything like that, it could be across the street.) "Come upon" and "come across" tend to be used when describing something you find while searching for something else or working on something else.

Like, "I was in the grocery store yesterday when I ran into my friend Sally." But, "I was searching the closet for my brown shoes when I came across some old photographs." You wouldn't normally switch the two. But the differences are subtle and if you did, it would sound only slightly odd.

Of course if you say, "I was driving down the street at 60 mile per hour when I ran into Sally", that means something quite different.

Answer 5

Come across something

Run into somebody

Answer 6

I will compare "run into" and "come across" in the meaning of "to meet something or someone". Those verbs have multiple meanings. "Come upon" is marked "literary" or "formal" in modern dictionaries.

run into somebody (rather informal): meet someone you know by chance. The key word here is "someone you know". In this meaning, it doesn't have any negative connotations:

I ran into an old neighbour of mine at the garage this afternoon.

You rarely run into people you know in London.

However, "run into something/someone" in the sense of "to crash (your vehicle) into it/them" is obviously bad.

come across something: to find something unexpectedly when you are not looking for it but are doing something else, as in:

Jill came across her son's diary when she was tidying his room one day.

come across somebody: to meet/find someone by chance, when you are not expecting it, as in:

You must have come across some weird and wonderful people while you were there.

I came across an old school friend of mine when I was travelling in Canada.

I came across a group of children playing.

He's the most unpleasant man I've ever come across.

I came across children sleeping under bridges.

My guess is that you usually run into people you know, whereas you come across people you know or total strangers.

Also notice the following examples where "run into" doesn't sound good or it changes the meaning of a sentence:

Just recently, I came across a familiar looking gorgeous man on facebook.

Was just on a dating website and came across my ex girlfriend on it?

Ever notice how you come across somebody once in a while you shouldn't have fucked with?

Your [sic!] going to come across a lot of shitty bands, and a lot of shitty people.

When you come across your crush, you feel like you are melting and as if you are going to faint.

With things, it's simple. When you find something by chance, you come across it.

The Oxford Phrasal Verbs Dictionary marks "come across sb/sth" as very common. It doesn't mark "run into" as common.

Sources: the Longman Phrasal Verbs Dictionary, The Oxford Phrasal Verbs Dictionary, the Cambridge Phrasal Verbs Dictionary, the Longman Language Activator, The Oxford Learner's Thesaurus