The Knowledge
Why Phoenix’s Skyline Has Stayed Low — And How It Compares to Los Angeles
Discover why Phoenix’s skyline lacks supertall skyscrapers, from FAA flight path limits near Phoenix Sky Harbor International Airport to how it compares with Los Angeles’s skyline growth.
Last Updated on March 25, 2026 by Daily News Staff
Phoenix is the fifth-largest city in the United States, yet its skyline doesn’t resemble other major metros like Los Angeles, Chicago, or Dallas. Despite rapid population and economic growth, downtown Phoenix has long lacked supertall skyscrapers — and until recently, didn’t even have a building tall enough to qualify as a true “skyscraper” under standard definitions.
The Basics: Phoenix’s Height Reality
The tallest structure in Phoenix for decades has been Chase Tower, rising to about 483 feet. Under the Council on Tall Buildings and Urban Habitat definition, a skyscraper reaches at least 492 feet — which means Phoenix has technically lacked one — despite its size and population.
A new project, the Astra Tower, is planned to rise around 540+ feet when it breaks ground, potentially giving Phoenix its first true skyscraper.
Airport Proximity: The FAA’s Height Grid
FAA Obstacle Evaluation & Downtown Limits
Phoenix’s skyline constraints are rooted in aviation safety.
📍 Phoenix Sky Harbor International Airport sits just a few miles from downtown.
- The Federal Aviation Administration (FAA) regulates building heights near airports so they don’t obstruct flight paths, require planes to alter approaches, or interfere with climb-out safety.
- In Phoenix, this results in a layered set of height limits that vary by location and elevation above sea level — often measured in feet above mean sea level (MSL) rather than simply building height from ground.
The city’s zoning code divides downtown into multiple contour zones with distinct maximum elevation values (e.g., 1,275 ft, 1,525 ft, 1,700 ft MSL), each tied to how close it sits under airport flight paths.
That means in some blocks you can’t build above a specific elevation even if ground levels are lower — a regulatory “roof” that varies across downtown.
City zoning also explicitly states that no building can exceed the FAA’s airport height limits, even if other bonuses or zoning allowances exist.
Phoenix vs. Los Angeles: A Quick Comparison
Los Angeles: Higher Limits, Different Constraints
Cities like Los Angeles also have nearby airports (e.g., Los Angeles International Airport), but their key business districts aren’t directly under major flight corridors.
LA’s downtown has:
- Taller office and residential towers
- A financial core with dense development
- Fewer FAA-driven overlays because the flight paths stretch past the downtown edge
Los Angeles’s tallest buildings — including Wilshire Grand Center (~1,100 ft) and U.S. Bank Tower (~1,018 ft) — were built where FAA restrictions don’t force low ceilings. FAA evaluations were conducted but didn’t cut as deeply into downtown zoning compared to Phoenix.
Phoenix, by contrast, sits right under approach and departure corridors — leading to consistent FAA involvement in almost every proposed mid- or high-rise downtown.
Economic and Planning Philosophies
Beyond FAA rules:
- Phoenix developed in the automobile era, with vast inexpensive land encouraging horizontal growth.
- Los Angeles grew earlier with heavier investment in centralized neighborhoods and higher density.
- Phoenix’s village plan long encouraged multiple smaller hubs instead of concentrating all growth in one downtown core.
These historical differences mean Phoenix didn’t have the same economic “pressure” to build up — even with zoning that allows significant height if FAA permits are met.
What This Means for Phoenix’s Future
Phoenix still has room to grow vertically — but:
- FAA height contours will remain the ceiling unless flight paths change
- Developers must secure determinations of no hazard from the FAA before going taller
- New projects like Astra show demand for taller buildings is rising
As Phoenix’s urban core densifies and land becomes scarcer, its skyline may yet reach higher — but always within the invisible grid drawn by aviation safety.
Related External Links
- Phoenix Sky Harbor International Airport Official Website
- FAA Obstruction Evaluation / Airport Airspace Analysis (OE/AAA)
- City of Phoenix Planning & Development Department
- Council on Tall Buildings and Urban Habitat (CTBUH)
- Los Angeles World Airports (LAX Authority)
- Phoenix Skyscraper Database & Diagrams
- Los Angeles Skyscraper Database & Diagrams
Dive into “The Knowledge,” where curiosity meets clarity. This playlist, in collaboration with STMDailyNews.com, is designed for viewers who value historical accuracy and insightful learning. Our short videos, ranging from 30 seconds to a minute and a half, make complex subjects easy to grasp in no time. Covering everything from historical events to contemporary processes and entertainment, “The Knowledge” bridges the past with the present. In a world where information is abundant yet often misused, our series aims to guide you through the noise, preserving vital knowledge and truths that shape our lives today. Perfect for curious minds eager to discover the ‘why’ and ‘how’ of everything around us. Subscribe and join in as we explore the facts that matter. https://stmdailynews.com/the-knowledge/
Forgotten Genius Friday
When people think about space exploration, they often remember the astronauts who traveled beyond Earth. But behind every mission are engineers, scientists, and inventors who create the technology that makes those journeys possible.
One of those innovators is Ellen Ochoa — an engineer, inventor, and astronaut whose work helped advance optical technology and opened new possibilities for space exploration.
Her story is not only about reaching the stars. It is about creating the tools that help humanity understand the world around us.
A Curiosity for Science and Discovery
Born on May 10, 1958, in Los Angeles, California, Ellen Ochoa developed an early interest in learning and problem-solving. She studied physics at San Diego State University before earning advanced degrees in electrical engineering from Stanford University.
Her path was shaped by curiosity, determination, and a passion for using science to solve real-world challenges.
Before becoming an astronaut, Ochoa was already making history as an engineer.
The Technology Behind the Vision
Ochoa specialized in optical systems — technology that allows machines to analyze and interpret images.
Her research led to inventions involving optical inspection systems designed to improve how computers process visual information. These technologies helped with tasks such as detecting defects, analyzing patterns, and improving automated systems.
Through her work, Ochoa became a co-inventor on several patents related to optical technology.
Her inventions demonstrated an important idea: exploration is not only about traveling farther — it is also about developing better ways to observe, measure, and understand.
Breaking Barriers at NASA
In 1990, Ellen Ochoa was selected as an astronaut candidate by NASA.
Three years later, she made history aboard the Space Shuttle Discovery mission, becoming the first Latina to travel into space.
During her NASA career, Ochoa completed four space missions and spent nearly 1,000 hours in orbit. Her missions focused on scientific research, Earth observation, and advancing our understanding of space.
She became a symbol of possibility for future generations of scientists, engineers, and explorers.
Leading the Next Generation of Space Exploration
Ochoa’s impact continued after her astronaut missions. She later became the first Latina to serve as director of NASA’s Johnson Space Center, helping guide one of the world’s most important space organizations.
Her leadership helped inspire new generations to pursue careers in science, technology, engineering, and mathematics.
A Legacy Beyond the Stars
Ellen Ochoa’s journey reminds us that innovation can come from many places. Sometimes the greatest discoveries begin with a question, an idea, or a new way of looking at a problem.
She did not just travel into space — she helped create the technology that made discovery possible.
For Forgotten Genius Friday, Ellen Ochoa represents what the series celebrates: the innovators whose brilliance changed the world, even before many people knew their names.
Her inventions helped us see the future. Her journey helped others believe they could reach it.
Learn More About Ellen Ochoa
- NASA – Ellen Ochoa Biography
- NASA Johnson Space Center
- National Women’s History Museum – Ellen Ochoa
- Encyclopaedia Britannica – Ellen Ochoa
- NASA STEM Education
- Google Patents – Search Ellen Ochoa’s Patents
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The Earth
Cement has a climate problem — here’s how geopolymers with add‑ins like cork could help fix it
Portland cement drives ~8% of global emissions. Learn how low-carbon geopolymers—enhanced with add-ins like cork—could cut concrete’s footprint.
Alcina Johnson Sudagar, Washington University in St. Louis
Concrete is all around you – in the foundation of your home, the bridges you drive over, the sidewalks and buildings of cities. It is often described as the second-most used material by volume on Earth after water.
But the way concrete is made today also makes it a major contributor to climate change.
Portland cement, the key component of concrete, is responsible for about 8% of global greenhouse gas emissions. That’s because it’s made by heating limestone to high temperatures, a process that burns a large amount of fossil fuels for energy and releases carbon dioxide from the limestone in the process.
The good news is that there are alternatives, and they are gaining attention.
Portland cement: A greenhouse gas problem
Cementlike substances have been used in construction for thousands of years. Architects have found evidence of their use in the pyramids of Egypt and the buildings and aqueducts of the Roman Empire.
The Portland cement commonly used in construction today was patented in 1824 by Joseph Aspdin, a British bricklayer.
Modern cement preparation starts with crushing the excavated raw materials limestone and clay and then heating them in a kiln at around 2,650 degrees Fahrenheit (about 1,450 degrees Celsius) to form clinker, a hard, rocklike residue. The clinker is then cooled and ground with gypsum into a fine powder, which is called cement.
About 40% of the carbon dioxide emissions from cement production come from burning fossil fuels to generate the high heat needed to run the kiln. The rest come as the heat converts limestone (calcium carbonate) to lime (calcium oxide), releasing carbon dioxide.
In all, between half a ton and 1 ton of greenhouse gas is released per ton of Portland cement. Cement is a binding agent that, mixed with water, holds aggregate together to create concrete. It makes up about 10% to 15% of the concrete mix by weight.
Alternative technologies can lower emissions
As populations, cities and the need for new infrastructure expand, the use of cement is growing, making it important to find alternatives with lower environmental costs.
Some techniques for reducing carbon dioxide emissions include substituting some of the clinker – the hard residue typically made from limestone – with supplementary materials such as clay, or fly ash and slag from industries. Other methods reduce the amount of cement by mixing in waste sawdust or recycled materials like plastics.
The long-term solution for reducing cement’s emissions, however, is to replace traditional cement completely with alternatives. One option is geopolymers made from earthen clay and industrial wastes.
Geopolymers: A more climate-friendly solution
Geopolymers can be made by mixing claylike materials that are rich in aluminum and silicon minerals with a chemical activator through a process called geopolymerization. The activator transforms the silicon and aluminum into a structure that will look like cement. All of this can happen at room temperature.
The major difference between cement and geopolymer is that cement is mainly made of calcium, whereas geopolymers are made of silicon and aluminum with some possible calcium in their structure.
These geopolymers have been found to possess high strength and durability, including resilience in freeze-thaw cycles and resistance to heat and fire, which are important requirements in construction. Studies have found that some geopolymers can provide comparable if not better strength than traditional cement and, because they don’t require heat the way clinker does, they can be produced with significantly lower greenhouse gas emissions.
Geopolymers can also be produced from a variety of raw materials rich in aluminum and silicon, including earthen clays, fly ash, blast furnace slag, rice husk ash, iron ore wastes and recycled construction brick waste. Geopolymer technology can be adapted depending on the clay or industrial waste locally available in a region. https://www.youtube.com/embed/NOj3p6m9M7Q?wmode=transparent&start=0 A brief history of cement and geopolymers. Geopolymer International.
An added advantage of geopolymers is that changes to the mixture can produce a range of features.
For example, I and my co-researchers at the University of Aveiro in Portugal added a small amount of cork industry waste – the leftovers from creating bottle corks – to clay-based geopolymer and found it could improve the strength of the material by up to twofold. The cork particles filled the spaces in the geopolymer structure, making it denser, which increased the strength.
Similarly, additives such as sisal fibers from the agave plant, recycled plastic and steel fibers can change geopolymer properties. The additives do not participate in the geopolymerization process but act as fillers in the structure.
The structure of geopolymers can also be designed to act as adsorbents, attracting toxic metals in wastewater and capturing and storing radioactive wastes. Specifically, incorporating materials like zeolite that are natural adsorbents in the geopolymer structure can make them useful for such applications as well.
Where geopolymers are used now
Geopolymers have been used in many types of construction, including roads, coatings, 3D printing, coastal environmental protection, the steel and chemical industries, sewer rehabilitation and building radiation shielding and rocket launchpad and bunker infrastructure.
One of the earliest examples of a modern geopolymer concrete project was the Brisbane West Wellcamp airport in Australia.
It was built in 2014 with 70,000 metric tons of geopolymer concrete, which was estimated to have reduced the project’s carbon dioxide emissions by as much as 80%.
The geopolymer market is currently estimated to be between US$7 billion and $10 billion, with the largest growth in the Asia-Pacific region.
Analysts have estimated that the market could grow at a rate of 10% to 20% per year and reach about $62 billion by 2033.
In several countries, greenhouse gas regulations and green-building certifications are expected to support the continued growth of geopolymers in the construction industry.
Expanding the use of cement alternatives
The advantage of using industrial wastes in geopolymers is a double-edged sword, however. The composition of industrial wastes varies, so it can be difficult to standardize the processing methods. The geopolymer components need to be mixed in particular ratios to achieve desired properties.
Producing the activator for the geopolymer, typically done in chemical facilities, can raise the cost and contribute to the carbon footprint. And the long-term data about these materials’ stability is only now being developed given their newness. Also, these geopolymers can take longer to set than cement, though the setting time can be sped up by using raw materials that react quickly.
Developing cheaper, naturally available activators like agricultural waste rice husk with sustainable supply chains could help lower the costs and environmental impact. Also, printing the recipe on the raw material packaging could help simplify the job of determining the mixing ratio so geopolymers can be more widely used with confidence.
Even though geopolymer technology has some drawbacks, these low-carbon alternatives have great potential for reducing emissions from the construction sector.
Alcina Johnson Sudagar, Research Scientist in Chemistry, Washington University in St. Louis
This article is republished from The Conversation under a Creative Commons license. Read the original article.
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For generations of Southern Californians, the Vincent Thomas Bridge has been more than a way to cross the Los Angeles Harbor. It has been a landmark, a symbol, and for many of us, a childhood memory.
Growing up in Southern California, I remember trips to San Pedro with my family and the excitement of visiting the waterfront. My parents would often take us to Fisherman’s Wharf, where they would buy fresh crab, shrimp, fish, and sometimes shellfish. Those trips felt like an adventure. The sights, the smells of the harbor, the boats moving through the water, and the activity around the port made San Pedro feel like a completely different world.
But one thing always captured my attention — the Vincent Thomas Bridge.
Standing below that massive green suspension bridge, I would look up in amazement. Seeing cars and trucks traveling high above us across the harbor seemed almost unreal. The bridge stretched across the sky like a piece of modern engineering, connecting San Pedro to Terminal Island while towering over the ships and waterfront below.
Even as a kid, I was fascinated by transportation. I was already drawn to trains and the movement of machines — the way different forms of transportation connected people and places. The Vincent Thomas Bridge fit right into that fascination. It was another example of how engineering could transform a landscape and bring communities together.
Opened in 1963, the Vincent Thomas Bridge became one of the most recognizable structures in the Port of Los Angeles. Named after California Assemblyman Vincent Thomas, who fought for years to make the connection a reality, the bridge represented growth, progress, and the importance of the harbor to Southern California.
Now, more than six decades later, this historic bridge is preparing for a major preservation effort.
The upcoming Vincent Thomas Bridge Deck Replacement Project is designed to extend the life of the structure by replacing the aging roadway deck and upgrading safety features. The bridge itself is not being replaced — instead, crews are preserving this piece of Southern California history so future generations can continue using and experiencing it.
The work will begin with preparation activities in 2026, followed by a planned full closure beginning in late 2026 while the deck replacement takes place. The goal is to reopen the bridge before the 2028 Olympic Games in Los Angeles.
For some people, a bridge is simply concrete, steel, and cables. But for others, it represents memories.
For me, the Vincent Thomas Bridge brings back memories of family outings, standing near the harbor, looking upward in wonder, and realizing how impressive the world of transportation and engineering could be.
Preserving the bridge is not only about maintaining a roadway. It is about protecting a landmark that has been part of countless Southern California stories — including mine.
The Vincent Thomas Bridge has carried millions of vehicles across the harbor. But it has also carried memories, dreams, and a sense of connection for generations of Angelenos.
And now, it is preparing for its next chapter.
Further Reading & Information
- Caltrans – Vincent Thomas Bridge Deck Replacement Project
- Caltrans – Vincent Thomas Bridge Deck Replacement FAQs
- Port of Los Angeles – Official Website
- LA Waterfront – San Pedro Waterfront Development
- San Pedro – History, Community & Waterfront Information
- California Highways – State Route 47 & Vincent Thomas Bridge History
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