How long does a tweet live before it gets buried in the scroll line? Someone told me less than 60 seconds. Is that accurate? –Paula Cappa, @PaulaCappa1 
I like this question because I see more implied here than is stated. On the lines, I read: “How long does a tweet live?” Between the lines, I read: “Does anyone actually see my tweets?” I hope you’ll forgive me if I’m projecting, Paula, but for the sake of this column I’m going to answer that projection as much as I’ll answer your literal question.
So, how long does a tweet live? Technically, all tweets last indefinitely, because anyone could do a search or otherwise come across any old tweet at any time. They can still read it, which means they can still “like” it (used to be “favorite”) or retweet it even if it’s five years old. To find the permanent link to an old tweet, click on the time stamp beside it, circled in red here:
This will open the tweet on its own page, like so:
Once the tweet is opened in its own page, you can copy the permalink URL from your browser bar. For the tweet screenshot above, the permalink is: https://twitter.com/AnnieNeugebauer/status/675078988612661248 
(This is useful if you want to imbed a tweet in a blog post or link to it on other sites; there are also options for “copy link to tweet” and “embed tweet” under the “more” dropdown, which looks like an ellipsis under your tweet.) The permalink will last until you delete the tweet. Or perhaps until Twitter deletes it, someday, in some sort of anarchist housecleaning fit. Who knows?
But “forever” is a frustrating answer, isn’t it? How long will the tweet show in the actual timeline, or scroll line as you call it, Paula?
Why not open your timeline and see? Go ahead, open another tab to Twitter and take a look at the top tweet. Depending on what kind of device you’re on, you might have to click the “show new tweets” bar or tweets might automatically refresh. For me just now, at the time of writing this, it only took 35 seconds for the top tweet to disappear below new ones. At that rate, 60 seconds sounds generous.
Very few people read tweets this way. Who sits there all day reading each tweet as it goes by? No one, hopefully. (Don’t do that.) What most people do is get on at certain times and scroll through their timeline, scanning and reading only the tweets that catch their eye. How many tweets they see depends on a widely varying array of factors: how many people they follow, how often the people they follow tweet, how often they get on Twitter to read tweets, and for how long, and how thoroughly, and whether they look at their main timeline or only at the timelines of specific lists.
That’s a lot of factors. On top of all of those are even more, such as how many times a tweet gets retweeted . Each person who retweets it increases the audience of said tweet by any number of their own followers (also influenced by all of the factors above). If you use hashtags  in a tweet, anyone looking at that hashtag’s timeline might also see your tweet, even if they don’t follow you. Not to mention that sometimes Twitter users might not look at their general timeline for days or even weeks but then might come check out your personal profile and read all of your latest tweets at once, perhaps retweeting one or two. On top of that, the tweet you have “pinned” to the top of your profile stays more easily visible for a long time (so choose wisely), giving it a longer lifespan.
In short? No one can tell you anything particularly useful about how long a tweet lives. Solid numbers not only vary, but can cause a sense of panic. My tweets only show for a minute? Maybe I should tweet the same thing ten times! Maybe I should tweet twenty times a day! And hey, that can increase your visibility; it can also decrease the quality of your followers and ultimately decrease the impact of what you’re doing. To me, five thoughtless retweets are worth less than one personal interaction that leads to a new reader. I’m all for quality over quantity , but everyone will have to find their own balance.
I do have some good news, though. You can’t measure the lifespan of a tweet, but you can measure its statistical success. If you’re not familiar already, I’d like to introduce you to an incredibly useful tool called Twitter analytics . Here, you’ll see a dashboard of your tweets. For each tweet, you can see exactly how many people have “seen” it (impressions) and interacted with it (engagements). You can look at your top tweets to see if there are trends in what’s working for you: subject, time of day, hashtag, etc. You can see your top @ mentions , profile visits, followers, and even your audience’s interests. In short, if you’re analytically-minded, this is a wonderland of information you can use to increase the statistical effectiveness of your tweets.
The key word here, though, is statistical. Yes, you want your tweets to be visible and yes, you want people to interact with them, but at the end of the day, numbers only take us so far. If you spend tons of time on Twitter so you can increase your numbers, but you’re left with no increase in book sales and no personal connections, what’s the point? If used correctly, Twitter holds value for writers far beyond Who Wins the Most Retweets contests, but then that’s a topic for another day.
So how long does a tweet live? Well, not very long – not most of them. But that’s okay, because that’s how Twitter was designed. It’s a platform for quick, short bursts of content. If only 100 people see your tweet, so what? You can put out as many as you want, and if you keep at it, eventually you’ll figure out how to make those 100 views count, how to increase that number to 1,000, or if you’re really good, both.
Do you have a question about Twitter that you’d like answered here on Writer Unboxed? You can leave your question in the comments below, fill out this quick, easy online form  – there’s an anonymous option if you’re shy – or simply tweet your question with the hashtag #AskAnnieWU . (You can send them to me directly @AnnieNeugebauer  as well.) I look forward to getting more of your questions!
Now, thanks to tinyCoffee and PayPal, you can!