Meanwhile, for the past 100 years, Brooklyn has been the city's most populous borough. While it has long enjoyed a measure of commercial relevance due to the presence of Downtown Brooklyn and a sizable number of industrial facilities, the majority of Kings County has long been dominated by single-family and multi-unit residences. However, over the past few years, investors have eyed the borough differently. Because of Brooklyn's large stock of warehouses and manufacturing facilities — properties primed for conversion to new-age, open-layout office spaces — the borough has seen many millions of square feet of office development and redevelopment. And while this trend is particularly pronounced in northern Brooklyn's waterfront areas, office development has skyrocketed across much of the borough. With these office properties attracting first-tier tenants like Kickstarter, Amazon and Vice Media, it's clear that Brooklyn has staked a claim as a viable, if not premier, commercial center.

These positive neighborhood changes have little downside. While Manhattan residential product is in growing demand, the borough is unlikely to threaten Brooklyn for the population crown. Similarly, while many companies, especially on the creative side, are drawn to the emerging office haven in Brooklyn, Manhattan's central location, transportation infrastructure and overall cachet will ensure that the borough's skyscrapers will not soon be found vacant.

Still, it's fascinating to see how the rejuvenation each borough is experiencing is, to a significant extent, concentrated in an area that complements its previous strengths, forging two boroughs that can largely operate as independent but cohesive cities.

In essence, New York is a tale of two cities. Again.

Michael Weiser is president of GFI Realty Services LLC, a New York City investment sales brokerage for multifamily, mixed-use and developable properties. The views expressed here are the author's own.

NEW YORK CITY—As students of New York history know, the current city boundaries were established in 1898. Prior to that, major portions of NYC — the bulk of the outer boroughs, constituting the vast majority of the Big Apple's square footage — were simply parts of Long Island and Westchester County, and made up the entirety of Richmond County. (This fact, you may know, also explains why the Dodgers were known as a Brooklyn franchise and not a New York one. When the ball club was formed in 1884, Brooklyn was still its own municipality.)

Upon the city's unification, New York, already the largest city in the country, added Brooklyn — what was the country's fourth-largest city — to its ranks, cementing its status as the country's largest market. Already a major city, the unified New York became the country's true gateway city.

While New York never lost this status, it did seem to lose a bit of its luster in the latter portion of the 20th century, as a modicum of urban decay took hold. But as the city has regained its cultural prominence and supreme global allure in recent years, it's interesting to see how several aspects of its resurgence demonstrate that, despite being one unified city for more than a century, to a large extent, Brooklyn and Manhattan can each operate as viable, independent ecosystems.

Despite the presence of numerous residential neighborhoods on the northern half of the island, Manhattan has, of course, long been dominated by the skyscrapers and other commercial properties in Midtown and Lower Manhattan. In recent years, we've seen a marked reinvigoration of Upper Manhattan — from Harlem and Hamilton Heights to Washington Heights and Inwood — due, in large part, to the strong transportation infrastructure these areas afford, and the proximity they have to both universities and the city's commercial center. With the market entrance of a range of neighborhood amenities including fresh dining, shopping and entertainment options, we've seen Upper Manhattan once again become a desirable residential area for families and young professionals.

Meanwhile, for the past 100 years, Brooklyn has been the city's most populous borough. While it has long enjoyed a measure of commercial relevance due to the presence of Downtown Brooklyn and a sizable number of industrial facilities, the majority of Kings County has long been dominated by single-family and multi-unit residences. However, over the past few years, investors have eyed the borough differently. Because of Brooklyn's large stock of warehouses and manufacturing facilities — properties primed for conversion to new-age, open-layout office spaces — the borough has seen many millions of square feet of office development and redevelopment. And while this trend is particularly pronounced in northern Brooklyn's waterfront areas, office development has skyrocketed across much of the borough. With these office properties attracting first-tier tenants like Kickstarter, Amazon and Vice Media, it's clear that Brooklyn has staked a claim as a viable, if not premier, commercial center.

These positive neighborhood changes have little downside. While Manhattan residential product is in growing demand, the borough is unlikely to threaten Brooklyn for the population crown. Similarly, while many companies, especially on the creative side, are drawn to the emerging office haven in Brooklyn, Manhattan's central location, transportation infrastructure and overall cachet will ensure that the borough's skyscrapers will not soon be found vacant.

Still, it's fascinating to see how the rejuvenation each borough is experiencing is, to a significant extent, concentrated in an area that complements its previous strengths, forging two boroughs that can largely operate as independent but cohesive cities.

In essence, New York is a tale of two cities. Again.

Michael Weiser is president of GFI Realty Services LLC, a New York City investment sales brokerage for multifamily, mixed-use and developable properties. The views expressed here are the author's own.