U.S. Domestic Nonstop Flights by City and Airline

U.S. Nonstop Flights by City and Airline

Seven carriers. 282 departing cities. Every scheduled nonstop route in the US domestic network for 2025, mapped by airline, ranked by city, and broken down by how many carriers compete on each route. The question this dashboard answers: which airlines operate the most domestic nonstop flights, which cities have the most domestic flight options, and where carriers compete head-to-head on the same routes, including where direct flights are available from multiple carriers.

Analytical Insights

The headline finding is blunt: two-thirds of US nonstop routes (1,846 of 2,789) are served by exactly one airline. Nearly nine in ten have no more than two carriers. Route-level competition in the US domestic network is the exception, not the rule.

The distribution follows a near-perfect power law. Routes served by a single carrier: 1,846 (66%). Two carriers: 646 (23%). Three carriers: 231 (8%). Each tier is roughly one-third the size of the one before. By the time you reach four or more carriers competing on the same route, you're looking at 66 routes out of 2,789, about 2.4% of the network. The entire six-carrier tier is just four routes, all Los Angeles to Hawaii: Honolulu, Kahului, Kona, and Lihue.

One nuance keeps that finding honest: competition tracks route size. The busiest, most prominent routes are contested: transcontinental lanes, Chicago to New York, LA to San Francisco, LA to Hawaii. What's single-carrier is the long tail of small- and mid-size markets, the hub spokes connecting Charlotte to Fargo or Dallas to Boise. On the routes most travelers actually care about, there's usually a choice. Across the network as a whole, a single airline is often the only option.

The Southwest Anomaly

The most structurally revealing finding is Southwest's density. Southwest flies 993 unique routes, nearly matching American's 1,005, from just 103 departing cities compared to American's 229. That produces a routes-per-city rate of 9.6 for Southwest versus 3 to 4 for the legacy carriers. American, Delta, and United build network size through hub concentration. Southwest builds it through a dense point-to-point web anchored at secondary airports: Dallas Love Field instead of DFW, Chicago Midway instead of O'Hare, Baltimore instead of Dulles.

The paradox this produces: Southwest, the low-cost alternative, holds the second-most monopoly routes in the network (431), trailing only American (528). It dominates secondary markets the legacy carriers don't fly.

Per-Airline Competitive Signatures

American is the largest network (1,005 routes) and the most insulated. At 53% exclusive routes, more than half of its network faces no competition from the other six carriers. It anchors at Dallas/Fort Worth, Charlotte, and Chicago.

JetBlue is the clearest contrast. Its most common route type is a duopoly, not a monopoly: 69 two-carrier routes versus 42 exclusive. With 76% of its routes facing at least one competitor, JetBlue is the only carrier in this dataset where competition is the norm rather than the exception. It operates primarily in the Northeast and Florida, in markets where other carriers also operate.

Hawaiian sits at the opposite extreme: only 1 of its 40 routes has no competition. Its routes cluster at three or more carriers, which reflects the LA-to-Hawaii corridor drawing every carrier with transpacific range.

Competitive-exposure ranking, from least to most contested: American (47% of routes face a competitor), Delta (52%), Southwest (57%), United (58%), Alaska (59%), JetBlue (76%), Hawaiian (97%).

Geographic Reach

American and United each reach 49 states. Delta reaches 48. Delaware is the only state with no scheduled nonstop service from any of the seven carriers. Southwest reaches 42 states from 103 cities. Hawaiian is the most concentrated at 11 states.

Los Angeles is the most contested city in the network. It anchors all four six-carrier routes (the LA-to-Hawaii lanes) and several highly competed transcontinental routes: LA to San Francisco, LA to San Jose, LA to Las Vegas. Seattle and Chicago rank next. Fortress hubs (Delta at Atlanta, American at Charlotte, Alaska at Seattle) generate high route counts with little competition. Battleground cities (Los Angeles, Chicago, New York, Las Vegas, San Francisco) are where the large networks collide.

Project Details

FieldDetail
Tools Used: Tableau Public, Tableau Prep
Data Source: U.S. DOT Bureau of Transportation Statistics; OurAirports
Airlines Covered: American, Southwest, Delta, United, Alaska, JetBlue, Hawaiian
Data Period: May 2026
Departing Cities: 282
Project Type: Personal Research Project
Published: 2026

Project Motivation

Airline route competition is public information that nobody has assembled into a usable picture. The DOT publishes the data; airlines don't hide it. But the coverage questions, which cities are served by one carrier only, where does real competition exist, which airline has the widest geographic reach, require building the dataset from scratch, deciding what counts as a route, and validating the numbers against multiple sources. The motivation was a specific question: for US domestic nonstop travel, how much of the network is actually contested versus effectively controlled by a single carrier?

How This Dashboard Was Built

The challenge: There's no tidy, public list of "every nonstop route each US airline flies." Airlines don't publish it, and the open datasets that exist are years out of date. Getting a complete, current, trustworthy picture meant going to the primary source and doing the data engineering by hand.

Sourcing the data: The foundation is the U.S. Department of Transportation's Bureau of Transportation Statistics. Its legacy download tools have been retired, so the data was pulled programmatically from BTS's current system, the Marketing Carrier On-Time Performance table for all of 2025 plus early 2026. "Marketing carrier" is the key choice: it attributes each flight to the brand a traveler actually books (American, Delta, United, etc.), which correctly folds in regional-affiliate flying like American Eagle, Delta Connection, and United Express.

Defining a "route" carefully: A surprising amount of the work was deciding what counts. The data was cross-checked against BTS's T-100 Domestic Segment table to strip out non-bookable movements, ferries, charters, and diversions, leaving only scheduled passenger service. It was filtered to the seven full-service and low-cost carriers (excluding ultra-low-cost airlines), limited to the 50 states plus Washington, D.C., and de-duplicated so each city pair counts once.

Building the dataset: Cities were matched to their airports and geocoded with latitude/longitude from OurAirports, so the maps plot exact coordinates instead of relying on name-matching (which fails on metro labels like "Dallas/Fort Worth"). The result was shaped into clean tables, one per airline, with departing/destination cities, states, and coordinates.

The dashboard: Data was modeled in Tableau Prep and visualized in Tableau: KPI tiles for total unique routes and single-carrier share, a per-city flight ranking, an airline-size comparison, a geographic-reach breakdown, and a route-competition distribution, all driven by a single airline selector.

Getting the numbers right: The final and most iterative phase was analytical accuracy, ensuring every metric used a consistent definition of a "route," that per-airline rankings recomputed correctly when filtered, and that the competition figures reflected unique city pairs rather than double-counted directions. The payoff is a dashboard where each number means exactly what it says.

Tools: BTS (data source) · OurAirports (coordinates) · Tableau Prep · Tableau (data pipeline assembled with AI-assisted coding via Claude Code).

Dashboard Features

Single dashboard with seven views, all driven by a single airline selector. An airline checklist filter and a spotlight parameter let viewers isolate or highlight any of the seven carriers across every view simultaneously.

The top section shows the percentage of routes served exclusively by one airline per carrier, a monopoly-route metric that varies significantly by airline. Below that, a side-by-side pair shows the top 10 departing cities by nonstop flight count with airline breakdown alongside total nonstop flight counts by carrier. A second side-by-side pair covers departing city and state counts per airline alongside the distribution of how many airlines compete on each route, broken into 1, 2, 3, 4, and 5+ carrier segments. The bottom view filters to routes with five or more competing carriers, showing the most contested city pairs in the network.

City scope is defined by city limits, not metropolitan area. Newark's EWR is excluded from New York. O'Hare and Midway are both included in Chicago since both airports sit within Chicago city limits.

Skills Enhanced

Multi-source BTS data pipeline, with programmatic extraction from the Marketing Carrier On-Time Performance table and cross-validation against the T-100 Domestic Segment table to strip non-passenger movements and ensure only scheduled service is counted.

Geocoding at city level using OurAirports coordinates, replacing name-based lookups that fail on ambiguous metro labels (Dallas/Fort Worth, New York/Newark). Each city plots at exact coordinates rather than a centroid guess.

Tableau Prep for data modeling, reshaping per-airline source tables into a unified schema before Tableau import, so the airline selector filter recomputes all metrics consistently rather than toggling between disconnected data sources.

Route deduplication logic, with city pairs counted once regardless of direction, using a calculated field that canonicalizes each pair (Departing City before Destination City alphabetically). This prevents double-counting and ensures the competition metrics reflect actual unique routes.

Single-parameter dashboard design, where one airline selector filter drives seven views simultaneously, including the monopoly-route percentage, city rankings, geographic reach, and competition distribution. Every metric recalculates on selection.

AI-assisted data pipeline coding via Claude Code to accelerate the BTS extraction and reshaping work.

Frequently Asked Questions

Which US airline has the most nonstop routes?

American, with 1,005 unique city pairs in the dataset. Southwest is close at 993, but operates from only 103 departing cities compared to American's 229, meaning Southwest concentrates more routes into fewer, busier markets. Delta and United follow at 786 and 772 routes respectively, both operating from roughly 200+ cities.

What percentage of US domestic nonstop routes have only one airline?

66%: 1,846 of 2,789 unique city pairs in this dataset are served by exactly one of the seven covered airlines. 23% are served by two carriers, 8% by three. Routes with four or more competing airlines are rare, only 66 total across the entire network.

Which airline has the highest share of monopoly routes?

American, at 53%: more than half of American's 1,005 routes have no competition from the other six carriers in the dataset. Delta is second at 48%. Hawaiian is the lowest at 2.5%, which makes sense, since Hawaiian's routes are concentrated in the LA-to-Hawaii corridors where every major carrier competes.

Which routes are the most competitive?

The four most contested routes in the network are all Los Angeles to Hawaii: Los Angeles to Honolulu, Kahului, Kona, and Lihue each have all six non-JetBlue airlines competing, namely Alaska, American, Delta, Hawaiian, Southwest, and United. On the continental US, Chicago to New York, Boston to Chicago, and Chicago to Seattle each draw five competing carriers.

Why does Southwest have almost as many routes as American despite serving fewer cities?

Southwest's network is built around high-frequency point-to-point flying in busy markets rather than hub-and-spoke distribution through regional airports. With 103 departing cities versus American's 229, Southwest achieves a similar total route count by running more routes per city in the markets it serves, particularly the densest leisure and business corridors.

Which US cities have the most domestic nonstop flights?

The cities with the most domestic nonstop flight options in this dataset are the major airline hubs: Atlanta (Delta's primary hub), Chicago O'Hare (American and United), Dallas/Fort Worth (American), Denver (United), and Los Angeles (all major carriers competing). Southwest's top cities by route count differ: Chicago Midway, Las Vegas, Denver, Phoenix, and Baltimore reflect its point-to-point model rather than hub concentration. The dashboard ranks all 282 departing cities by total nonstop flight count, with airline breakdown visible for each city.

How is a route defined here?

A unique city pair counted once, regardless of direction. Dallas to Chicago and Chicago to Dallas are one route. The data is filtered to scheduled passenger service only, cross-checked against BTS's T-100 table to remove charter, ferry, and diversion movements. City scope is defined by city limits, not metropolitan area: Newark counts separately from New York, but both O'Hare and Midway are included in Chicago.

What is the difference between a direct flight and a nonstop flight?

A nonstop flight has no stops between origin and destination: wheels up in City A, wheels down in City B. A direct flight may stop at an intermediate city but doesn't require passengers to change planes. The two terms are used interchangeably in everyday conversation, but airlines and the DOT distinguish them. All routes in this dashboard are true nonstop, no intermediate stops. When people search for "direct flights from Dallas to Chicago," they typically mean nonstop. This dashboard maps every nonstop domestic route across seven major carriers.