Last revised: August 9, 2026
By: Adam Burns
The history of the Class I railroad traces back to the nation’s first common carrier, the Baltimore & Ohio. Over the next century more than 140 systems wore the designation. After World War II, mergers, bankruptcies, and takeovers reduced the field to today’s six Class I freight railroads recognized by the Association of American Railroads (AAR) for U.S. freight service:
Burlington Northern Santa Fe C44-9W #4723, the official Microsoft Train Simulator locomotive, is seen here on display at St. Louis Union Station in May, 2001. American-Rails.com collection.
These carriers hold the bulk of U.S. freight-rail route miles, employees, and freight revenue. They concentrate on long-haul, high-density intercity traffic—a sharp contrast with the classic era, when railroads also chased local and less-than-carload business. A true single-system Atlantic–Pacific freight railroad remains unrealized; whether that changes depends in part on the pending Union Pacific–Norfolk Southern merger case before the Surface Transportation Board (STB) (see below).
Related industry pages: Regional Railroads · Short Lines · Industry History · Fallen Flags.
| Item | Detail |
|---|---|
| U.S. Class I freights (AAR count) | Six: BNSF, UP, CSX, NS, CN (U.S.), CPKC |
| STB Class I revenue threshold (2025) | About $1.095 billion in annual operating revenue (inflation-adjusted; see definition below) |
| STB Class II threshold (2025) | About $49.1 million |
| U.S. freight rail network | Nearly 140,000 route miles (all freights) |
| Class I share of industry (AAR) | Roughly 67% of mileage, 87% of employees, 94% of freight revenue |
| Short lines / regionals (AAR) | About 615 Class II and III freights |
| Industry employment (AAR, recent) | About 153,000 direct rail jobs; far larger total economic impact |
| Class I pay package (AAR range) | Average annual wages + benefits often cited from about $135,000 into the high $100,000s (varies by year and source) |
| Fuel efficiency (industry messaging) | On the order of one ton of freight moved hundreds of miles per gallon of fuel—confirm current AAR fact sheets for the exact figure you cite publicly |
Industry statistics change year to year. Prefer primary AAR and STB releases when you need a single official number. Figures above compiled August 9, 2026 from public STB and AAR materials.
While the dollar figure that defines a Class I has changed repeatedly, the idea has not: a Class I is a railroad in the top revenue tier under federal classification rules. Today that classification is set by the Surface Transportation Board under 49 C.F.R. Part 1201, not by informal industry usage alone.
For regulatory purposes the STB groups carriers as Class I, II, or III by annual operating revenue. Thresholds are expressed in nominal dollars but adjusted for inflation from a published base year using a railroad revenue deflator. In a major reset effective for reporting years after the Board’s 2021 rulemaking, the Class I floor was raised from $250 million (1991 dollars) to $900 million (2019 dollars), with Class II adjusted upward as well. Annual deflator factors then convert those bases into current-year dollars.
For 2025 (the most recent year for which the Board has published deflator factors as of this revision), the STB lists approximately:
Source: STB Economic Data (Revenue Deflators). Always re-check the Board’s current EP 748 / deflator publication before citing a threshold in formal work.
Trade usage sometimes still quotes the $900 million (2019 dollars) base or older ladders. For American-Rails.com purposes, treat the STB inflation-adjusted figure for the year in question as authoritative, and note the base-year change so older books and articles do not confuse readers.
| Period / year | Approximate Class I floor (as commonly cited) |
|---|---|
| 1939 | $1 million annual operating revenue |
| 1956 | $3 million |
| 1965 | $5 million |
| 1976 | $10 million |
| 1978 | $50 million |
| 1992 / 1993 era | $250 million (1991 dollars)—long-standing ICC/STB base |
| 2010s–2019 (examples) | Inflation-adjusted figures such as ~$319M (2005), ~$476M (2014), ~$505M (2019) |
| Post-2021 rule (base) | $900 million in 2019 dollars |
| 2025 (STB published) | About $1.095 billion |
During the industry’s classic era, a Class I could be only a few hundred miles long if it met the revenue test. Small names such as the Detroit & Mackinac, Lehigh & Hudson River, Green Bay & Western, and Spokane International once wore the label. Today no freighter shorter than a multi-thousand-mile continental system sits in the Class I club; CPKC is the smallest of the six by route miles among the North American giants, but still far larger than any regional.
It’s the early Burlington Northern Santa Fe era as a pair of former Santa Fe GP60M’s, led by #129, along with BNSF C44-9W (#1014), work an eastbound up the west side of Cajon Pass at Blue Cut, California in June, 1997. American-Rails.com collection.
Federal regulation, highway and water competition, and the passenger-train crisis pushed railroads toward consolidation. Mergers and abandonments shrank the map from the 1916 peak of about 254,000 route miles to roughly 140,000 today. Class I systems own on the order of two-thirds of that mileage; much of the rest was spun off after the Staggers Rail Act of 1980 to short lines and regionals that now number in the hundreds.
Western duopoly (BNSF and Union Pacific) and eastern duopoly (CSX and Norfolk Southern) define most domestic long-haul freight geography, with the Mississippi River a rough dividing line. Canadian National and CPKC supply critical north–south and cross-border routes, including CN’s mid-continent U.S. network and CPKC’s Canada–U.S.–Mexico single-line franchise.
On March 21, 2021, Canadian Pacific announced it would acquire Kansas City Southern. Rival Canadian National offered a higher bid, but the STB rejected CN’s voting-trust approach on August 31, 2021. CP completed the purchase of KCS into a voting trust on December 14, 2021; after final STB approval on March 15, 2023, CP and KCS combined as Canadian Pacific Kansas City (CPKC) on April 14, 2023—the first single-line railroad linking Canada, the United States, and Mexico under one banner. KCS no longer exists as a separate Class I.
Full profile: Canadian Pacific Kansas City.
In the modern age it is unlikely a greenfield Class I will appear, though the idea is not impossible. In the 1990s, a growing Wisconsin Central approached the old revenue threshold after rebuilding Soo Line castoffs into a profitable midwestern system; Canadian National purchased WC in 2001. A similar regional growth story today would almost certainly involve acquisition rather than new main-line construction. Extensive environmental review, land-use opposition (“NIMBY”), and capital cost make major new corridors rare—the long-fought Tongue River Railroad coal project in Montana, first proposed in the 1980s, was ultimately rejected by the STB in 2016.
Reviving long-abandoned mains (for example, Milwaukee Road’s Pacific Extension or portions of Erie Lackawanna’s Chicago line) remains a favorite railfan speculation. A few short rebuilds have occurred since the 1990s, and many rights-of-way are railbanked for possible future freight use, but a multi-state Class I-scale reactivation would be extraordinary.
Union Pacific power, including GP40X #9000, along with C30-7 #2497 and SD40-2 #3185, layover at Rio Grande’s Burnham Shops in downtown Denver, Colorado, in the summer of 1982. Barely visible in the background is Union Pacific 4-8-4 #8444, which was hosting excursions from Denver to Sterling. Mike Bledsoe photo. American-Rails.com collection.
Earlier versions of this page used Excel-generated bar charts of Class I annual revenue through about 2022. Those graphics are retired. Company totals below are approximate full-year operating or total revenues as reported by each railroad (or widely reported from those filings). Canadian carriers report primarily in Canadian dollars; USD equivalents move with exchange rates—use company filings for precision.
Always verify the latest 10-K / annual report or investor release before treating any figure as definitive. Compiled August 9, 2026 from public earnings releases and secondary summaries of those releases.
| Railroad | 2023 (approx.) | 2024 (approx.) | 2025 (approx.) | Notes |
|---|---|---|---|---|
| Union Pacific | — | Freight revenue ~$22.8B; total operating revenue in mid-$20B range | Operating revenue about $24.5B | Western Class I; largest or near-largest U.S. freight revenue in recent years |
| BNSF Railway | — | About $23.3–23.4B | About $23.4B (essentially flat y/y in public summaries) | Berkshire Hathaway; private reporting via parent / BNSF financials |
| CSX Transportation | About $14.7B | About $14.5B | About $14.1B | Eastern Class I; coal and mix shifts continue to matter |
| Norfolk Southern | — | Railway operating revenue about $12.1B | About $12.2B | Eastern Class I; 2023 East Palestine event and recovery affect multi-year comparisons |
| Canadian National | About C$16.8B | About C$17.0B | About C$17.3B | Systemwide CAD; U.S. subsidiaries are Class I for STB reporting |
| CPKC | Partial first year as combined system | About C$14.5B total revenues (company reports) | Freight revenues on the order of C$14.8B+; total revenues ~C$15B class (confirm annual report) | Combined CP+KCS from April 14, 2023; Canada–U.S.–Mexico single line |
For sortable multi-year series and official U.S. regulatory data, use:
Burlington Northern Santa Fe SD70MAC #8957, wearing the “Heritage II” livery, and SD70MAC #9787, sporting the “Executive” scheme, have a cut of loaded coal hoppers at Oregon, Ohio on the Norfolk Southern in March, 2002. American-Rails.com collection.
In late July 2025, Union Pacific and Norfolk Southern announced an agreement aimed at creating what the companies call America’s first true transcontinental freight railroad. An initial STB application was filed in December 2025; after completeness issues, a revised major merger application was refiled in spring 2026, and the Board’s review process has continued with supplemental filings through mid-2026. As of this revision the merger is not consummated—approval, denial, or conditioned approval remains with the STB.
If approved without structural carve-outs that change the outcome, the industry would likely move from today’s six large freights toward a structure with one coast-to-coast U.S. giant opposite BNSF in the West and a reconfigured East—exactly the sort of map redraw that past CP–NS and CP–CSX proposals only hinted at in the 2010s. Shippers, labor, ports, and competing railroads are active parties; treat all synergy claims and opposition filings as advocacy until the Board rules.
Official docket materials: STB Major Railroad Mergers (UP–NS proceeding).
Earlier CP approaches to Norfolk Southern (2015–2016 under then-CEO E. Hunter Harrison) and informal talk of other eastern pairings remain useful historical context: they show how close the industry has repeatedly come to a two-system North American freight map—and how difficult multi-jurisdictional approval remains.
Class I freights move the bulk of U.S. rail ton-miles: intermodal containers and trailers, chemicals, grain and agricultural products, coal (still important though reduced from its peak share of rail revenue), automotive, metals, forest products, and aggregates. They interchange with hundreds of short lines that provide first- and last-mile industrial access. Capital intensity is extreme; AAR materials note tens of billions of private capital reinvested over decades into track, bridges, terminals, and locomotives—one reason new entrants struggle to reach Class I scale.
For passenger context (Amtrak and commuter agencies are not Class I freights under the AAR six-railroad freight list), see Amtrak and Commuter Rail.
Revenue thresholds, carrier counts, and merger status change. Confirm STB classification figures and company financials on official sites before relying on any single year’s number. Information compiled August 9, 2026.
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