Oakland’s propensity for transforming its landscape, skyline and demographics with confounding speed has always made the history of the city an intriguing subject to study and share.

But for some, a fondness of the past isn’t what has them digging through Oakland’s historical archives.

For Liam O’Donoghue, an Oakland resident for almost a decade, sifting through the detritus of past building booms is about learning how to counterbalance the economic forces that displace people.

To illustrate his point, O’Donoghue, a podcast host and DJ, teamed with T.L. Simons, owner of Front Group Design, to create Long Lost Oakland — a map that features long-forgotten structures, as well as extinct plants and animals.

The map’s topography dates to 1857, revealing an environment that’s been altered by industrialization. You can see that Lake Merritt was once a huge tidal estuary. It all looked very different back then, of course — a medium-size town with cattle trails and a growing waterfront trade that was about to boom with its designation as a major rail terminal.

Oakland is still changing so fast that walking around some of its neighborhoods can be disorienting. You might need a map to navigate the changes, but Long Lost Oakland is more than a map.

It’s really an invitation to learn about Oakland’s history, an opportunity to engage in a civics lesson. And this lesson — this historical context — is crucial if you want to understand why problems such as economic disparities and housing insecurities exist today.

“This map is sort of about grounding ourselves in the place that we live by understanding the history of how we got here,” O’Donoghue said.

We were sitting in Luka’s Taproom and Lounge Bar one evening last month. The restaurant, at the corner of West Grand Avenue and Broadway, used to be the site of the Key Route Inn, one of the buildings featured on the hand-drawn map. The hotel straddled Grand Avenue, and Key cars would go through the building.

Now it seems the two most prominent developments sprouting in Oakland are homeless camps and upscale condos.

“If you walk downtown right now, it’s a construction site,” O’Donoghue, 38, said. “There are cranes everywhere.”

“At lunch, downtown is just one big cafeteria for construction workers,” said Simons, 35, who drew the map.

I’ve learned a lot about one of the cities I cover by listening to “East Bay Yesterday,” O’Donoghue’s podcast on local history. The Long Lost Oakland project is accompanied by a miniseries of podcasts produced by him.

In one powerful episode, O’Donoghue discusses the black migration to the East Bay during World War II.

He tells the story of the diaspora through the history of the Moore Dry Dock Co., the shipyard that attracted blacks from the South looking for sustainable employment — and an escape from the brutal disenfranchisement of the South’s Jim Crow laws.

The company is one of the more than two dozen items featured on the Long Lost Oakland map.

In 1940, Oakland had about 8,500 black people, which was about 3 percent of the city’s population, according to O’Donoghue’s research. By 1950, the number had soared to almost 50,000.

But the shipyards in Oakland, Richmond and other coastal cities also drew poor whites from Southern states who brought along their racial attitudes and stereotypes.

There wasn’t enough housing for the influx of people, and blacks were subjected to public housing segregation and discriminatory lending policies endorsed by the federal government.

Housing covenants and redlining, the illegal practice of withholding and refusing services to communities of color, kept black people living in unstable neighborhoods.

In “The Color of Law: A Forgotten History of How Our Government Segregated America,” by Richard Rothstein, a senior fellow at the Haas Institute at UC Berkeley, connects the flagrant, systemic racism to the inequality that persists in neighborhoods and schools today.

In Oakland, the black population continues to fight housing scarcity, including many who don’t find themselves on the street.

According to a survey administered by Alameda County, almost 70 percent of the people living on Oakland’s streets are black. Yet black people were just 28 percent of Oakland’s 2010 census population. Just 30 years before, black people were 47 percent of the city’s population.

We should be asking ourselves: Why is this part of Oakland’s history?

“We don’t ask why enough in this country,” said Dorothy Lazard, a librarian at the Oakland Public Library who runs the Oakland History Room. “We always talk about the problem, but we can never solve the problem until we ask: Why did this happen? How did this happen? We’re not doing that enough.”

Lazard, who was featured in the Moore Dry Dock podcast episode, told me that new development erodes what came before.

“History is being rewritten very rapidly, but it’s also being forgotten very rapidly,” said Lazard, who was raised in Oakland after her family was forced to move out of San Francisco’s Western Addition neighborhood in 1970 because of urban redevelopment. “When people have that kind of attitude, it creates this huge and very hurtful and destructive kind of narrative where it’s an erasure, and that’s what’s painful about gentrification.”

It’s happened before. Oakland was built on indigenous land. The Ohlone lived here for thousands of years before colonization. Ohlone shell mounds, sacred burial sites, have been bulldozed by developers.

“Part of the reason we did this map is a reaction to what’s happening in Oakland,” O’Donoghue told me. “When we’re thinking about what we want Oakland to be in the future, you have to learn from past mistakes. We have to understand the strategies people used to create the Oakland that we live in now.”

We have to understand our shared history.

The colorful map is a reminder that nothing is set in stone.

San Francisco Chronicle columnist Otis R. Taylor Jr. appears Mondays and Thursdays. Email: otaylor@sfchronicle.com Twitter: @otisrtaylorjr