TWO SEASONS

In the north they joke that the year has only two seasons. The joke is a fair summary of a hard fact: frost breaks the road all winter, and crews race to fix it in the few warm months. Behind the orange cones sits a question every town argues about: who owns this road, and who pays for it?

Room 1 · WinterWhy roads break

A road is a stack: a hard skin of asphalt or concrete on layers of crushed stone and soil. Water gets in through hairline cracks. When it freezes it expands by about nine percent, prying the crack wider and lifting the layer above; when it thaws it leaves a void, and the next heavy truck breaks the weakened skin into a pothole. One winter can bring dozens of these cycles, which is why potholes peak in late winter and early spring, not in the deep cold.

Cities fight ice with salt and brine. The U.S. Geological Survey estimates that about 37 percent of all salt used in the country in 2025 went to highway deicing, out of roughly 57 million metric tons consumed. Salt lowers the freezing point of water, but it also rusts steel reinforcing bars inside bridge decks and runs off into streams: a cost the driver never sees, which economists call an externality.

Days below freezing, by state

gap The state map of freezing nights is not drawn yet: NOAA's Comparative Climatic Data station table (mean days with a low of 32°F or colder) has moved and could not be fetched. Until it is loaded, the rule of thumb holds: the northern tier and the mountain West see 120 to 180 freezing nights a year, the Gulf Coast and Florida only a handful, and the road-building season is roughly the frost-free part of the year. Look up any city in NOAA's U.S. Climate Normals.

Room 2 · Who pays for which roadLocal miles, state money, a federal tax that stood still

The United States has about 4.2 million miles of public road. Most of it is not interstate highway at all: it is county roads, township lanes and city streets. In 2023, local governments owned about 3.2 million miles, state highway agencies about 825,000, and federal agencies (parks, forests, military land) about 159,000. The Interstate System is only about one percent of all road miles, but it carries about a quarter of all driving.

FHWA, Highway Statistics 2023, table HM-10 (rural plus urban; 18 miles unreported). Florida columns from the same table.

The money runs the other way. In 2024 governments spent about $332 billion on highways. States spent 62 percent of it ($206 billion), local governments 36 percent ($121 billion), and federal agencies directly only about 2 percent ($5 billion), because Washington mostly hands its money to the states. Counted by who raises the money, the federal share is larger: about 16 percent, $54 billion, most of it from the Highway Trust Fund.

FHWA, Highway Statistics 2024, table HF-10 (preliminary in part); shares and revenue split from FHWA, Our Nation's Highways 2026. Note that local governments spend more on maintenance than states do: they own the most miles.

The federal gas tax: 18.4 cents since 1993

The federal tax on gasoline has been 18.4 cents a gallon since October 1993 (the last 4.3 cents moved into the Highway Trust Fund in 1997). It is a fixed number of cents, not a percentage, so inflation eats it. Prices have risen about 2.2 times since 1993: today's 18.4 cents buys what about 8.5 cents bought then. Cars also burn less fuel per mile, and electric cars pay none. Since 2008 Congress has moved well over $250 billion from the general fund into the Highway Trust Fund to keep it solvent.

check The "well over $250 billion" in general-fund transfers is a rounded figure from Congressional Budget Office and CRS summaries; check the current total before print.

State gas taxes

Federation of Tax Administrators, State Motor Fuel Tax Rates (2025), gasoline excise only. Several states add a sales tax on fuel (California, Connecticut, Illinois, Indiana, Michigan) or index the rate to inflation, so the price at the pump can include more. Florida's 37.3¢ includes its state fuel taxes; counties add local option taxes on top.

The 2021 infrastructure law, and what came after

The Infrastructure Investment and Jobs Act (2021), also called the Bipartisan Infrastructure Law, authorized about $1.2 trillion over five years, about $550 billion of it new spending, with roughly $350 billion for highways. Its surface transportation programs expired on September 30, 2026. A short-term extension carries the Highway Trust Fund programs to December 11, 2026, but the extra money the law had appropriated in advance was not extended, and Congress has not yet passed a new long-term highway bill.

Sources: CRS, Surface Transportation Reauthorization: Federal Highway Programs (R48845); NADO, "IIJA Funding Expired September 30" (2026). check status changes quickly; verify before teaching.

Room 3 · The cost of a mileResurface ten miles, or build one?

Every road budget is a choice between keeping what exists and building more. Florida's Department of Transportation publishes average costs per mile, built from the prices it actually paid contractors. They leave out bridges, intersections, signals and land, so real projects cost more, but they show the scale.

Florida Department of Transportation, Cost Per Mile Models (latest edition, weighted averages of awarded prices from about 18 months before the update). Rounded to $0.01 million. Conceptual: excludes structures, right-of-way, intersections and signals.

For the price of one mile of new urban interstate, a county could resurface about thirty miles of two-lane road. That is why so much of the warm season goes to milling and resurfacing: it is the cheapest way to keep the most miles open.

Bridges

The National Bridge Inventory rates every public bridge longer than 20 feet. Under the old measure, "structurally deficient" bridges fell from 21.7% of all bridges in 1992 (124,072 of 572,629) to 13.1% in 2005 and 8.9% in 2017. Since 2018 the inventory rates bridges good, fair or poor by their weakest part. In the inventory file Urbanicity holds (624,193 bridges), 6.7% are rated poor, 49.6% fair and 43.7% good.

Share of bridges rated poor, by state: Bureau of Transportation Statistics, National Transportation Atlas Database, National Bridge Inventory layer as loaded by Urbanicity. Poor = lowest of deck, superstructure, substructure or culvert rated 4 or less.

Room 4 · Where roads meet ships and trainsIntermodal nodes and ports

Roads do not end at the coast. A container can cross the Pacific by ship, ride a train to Chicago and finish the trip on a truck without being opened. The places where freight changes mode are intermodal terminals: ports with rail spurs to the dock, and inland yards where cranes lift containers and trailers between trains and trucks. The map shows the 150 principal ports by the weight of cargo they handled in 2023, and the rail-truck terminals the Bureau of Transportation Statistics lists.

Lower 48 only (Alaska, Hawaii and Puerto Rico ports are in the table). Ports: U.S. Army Corps of Engineers, Principal Ports (2023 tonnage, BTS National Transportation Atlas Database). Terminals: BTS, Intermodal Freight Facilities, rail TOFC/COFC (240 shown).

Close to home. Port Manatee, on Tampa Bay just north of Bradenton, bills itself as the closest U.S. deepwater seaport to the Panama Canal; it handles fruit juice, fertilizer, steel, cement, containers and fuel, has its own rail line to the national network, and sits minutes from I-75 and I-275. Port Tampa Bay, Florida's largest port by tonnage, moves fuel, phosphate and fertilizer for the region. Every truck that leaves either port uses roads that a county, the state or the federal government had to build and still has to keep.

Room 5 · The long runMiles built, roads maintained

The road network barely grew in length over the last century, from about 3 million miles around 1920 to 4.2 million today. What changed was what those miles are made of and who keeps them. In 1941 fewer than one mile in five was paved; by 2007 about two in three were. The rail network went the other way: from its 1916 peak of 254,037 route miles it shrank to about 140,000. Pick a year to compare.

Decade by decade

Lane-miles: BTS NTS table 1-6 (1980–2014), HM-60 (2023). Added per decade: 1980s about 129,000; 1990s about 173,000; 2000s about 357,000; 2010–2023 about 328,000. A year in brackets means the nearest year with data. Bridge measures changed in 2018 (structurally deficient → poor), so the last column breaks there.

SourcesWhere the numbers come from

• FHWA, Highway Statistics 2023, table HM-10 (public road length by ownership): fhwa.dot.gov/policyinformation/statistics/2023/hm10.cfm; HM-60 (lane-miles): …/2023/hm60.cfm
• FHWA, Highway Statistics 2024, table HF-10 (disbursements by level of government): …/2024/hf10.cfm; HF-10 for 2010 and 2000.
• FHWA, Highway Statistics Summary to 1995, tables HM-210 (miles by jurisdiction), HM-212 (miles by surface type) and HF-210 (funding, 1921–1995): fhwa.dot.gov/ohim/summary95/
• FHWA, Our Nation's Highways 2000, capital and maintenance expenditures 1968–2000: fhwa.dot.gov/ohim/onh00/line14.htm; Our Nation's Highways 2026: roads and funding and spending
• FHWA, Status of the Interstate System as of December 31, 1997: fhwa.dot.gov/highwayhistory/data/page06.cfm
• BTS, National Transportation Statistics tables 1-4 (road miles by surface) and 1-6 (lane-miles): bts.gov
• FHWA deficient bridges by highway system, 1992, 2005, 2017: fhwa.dot.gov/bridge/deficient.cfm; National Bridge Inventory layer, BTS NTAD.
• Florida Department of Transportation, Cost Per Mile Models: fdot.gov/fpo/fpc/reports/costpermile
• Federation of Tax Administrators, State Motor Fuel Tax Rates (2025): taxadmin.org
• U.S. Geological Survey, Mineral Commodity Summaries 2026, Salt: pubs.usgs.gov
• NOAA NCEI, Comparative Climatic Data (mean days with minimum 32°F or less) and U.S. Climate Normals: ncei.noaa.gov (state freeze map pending; see Room 1).
• U.S. Army Corps of Engineers, Principal Ports, 2023 tonnage (BTS NTAD); Houston Ship Channel 2023 ranking: txgulf.org
• CRS R48845, Surface Transportation Reauthorization: everycrsreport.com; NADO on the IIJA expiration: nado.org
• Rail route miles: Historical Statistics of the United States, Series Q 284, as on Rails, Spurs and the Truck. Consumer price index: BLS CPI-U annual averages.

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