LINCOLN — On the windswept plains of South Dakota lies a lonely, century-old historical monument holding a literary mystery and wrapped up in a legal conundrum.

The concrete capsule honors mountain man Hugh Glass, who crawled, limped and rafted 200 miles after being mauled by a grizzly bear and left for dead by his colleagues in 1823 near modern-day Lemmon, South Dakota.

How can neighborhoods gentrify without erasing their heart and voice?

You’ve seen the ads in your neighborhood. They’ve flashed across your television and buzzed your phone to life at odd hours. The slogans and phone numbers might change, but the pitch is the same: “We buy houses for cash.”

Thousands of real estate investors across the country use a variety of techniques to find potential sellers and plan their next deal.