Since Facebook claims to have used only anonymized and aggregated data, however, we can't know if those people opted to be single or are simply unloveable. Similarly, Facebook also lists cities with "the largest probability of relationship formation for a single person," but it doesn't explain its methodology nor does it give us any figures. El Paso might indeed be one of the best places for single people to find love (also, killer tacos), but, based off this chart alone, we can't know if the difference between, say, San Antonio and Colorado Springs is as significant as it looks.
Facebook also breaks down the most single females per male by city, and vice versa, but that doesn't necessarily mean those people are eligible for the opposite sex. San Francisco is the top city for single males per single female, but you could argue that its numbers are skewed because of its higher population of gay men. Then again, we weren't given real numbers, so we can say anything we want.
At the end of the day, however, what kind of actionable information does this data actually give us? If you're the kind of person who will pack up your bags and move to Detroit to find love, bonne chance. You'll definitely be able to find a vacant house there, too. (Facebook)