The word shortage entered federal transportation law in 2012 without a number attached to it. Section 1401 of the Moving Ahead for Progress in the 21st Century Act, known as Jason’s Law, established a national priority for projects addressing the shortage of long-term parking for commercial motor vehicles on the National Highway System, and section 1401(c) told the department to find out how big it was.
The instruction that followed is the part worth reading. The survey and comparative assessment was to evaluate each state’s capability to provide adequate parking and rest facilities for commercial motor vehicles in interstate transportation, assess the volume of commercial motor vehicle traffic in each state, and develop a system of metrics to measure adequacy. Congress asked for a measurement instrument rather than a count.
Two national inventories, and a comparison that does not reconcile
The first report landed in August 2015. Each state department of transportation was asked to inventory the location and number of spaces it maintained on the National Highway System, and the private supply was compiled from a commercial truck stop database published that year. The result was about 309,000 spaces, roughly 12 percent at public rest areas and 88 percent at private truck stops, giving 7.63 private spaces for every public rest area space nationally. Facilities are small, with roughly 39 percent providing between 1 and 24 spaces, and more than half contain no shower, which is a fact about whether a space is usable for a ten-hour rest rather than about whether it exists.
FHWA presented the second round on December 1, 2020, covering 2019 fieldwork. It reports approximately 313,000 spaces nationally, 40,000 at public rest areas and 273,000 at private truck stops, and it reports the change from 2014 to 2019 as a 6 percent increase in public spaces and an 11 percent increase in private ones.
Those two statements do not reconcile. Rounded against the 2015 inventory, the public total rises by roughly a tenth rather than by 6 percent, and the private total barely moves rather than rising by 11 percent. The percentages and the totals rest on different tabulations, so a reader who needs the growth rate cannot derive it from the published national figures.
The state-level comparison in the same deck is more informative anyway. Its 2014-to-2019 chart of public spaces shows counts falling in a number of states over exactly the period in which the national public total rose. Rest area closures cut supply in specific places while the aggregate rises.
Each figure belongs to its own respondent group
The 2019 round is the larger of the two and its response bases are published individually. All 50 state departments of transportation responded, a 100 percent rate. Safety enforcement agencies in 45 states responded, which the deck records as a 309 percent increase over 2014. Working through the American Trucking Associations, the Owner Operator Independent Drivers Association, Real Women in Trucking and Trucker Path, FHWA collected 11,696 driver responses and 760 from trucking operations managers, plus 524 from truck stop operators through NATSO and 18 from port authorities, a group surveyed for the first time.
Keeping those bases straight matters because the most-quoted figure in this subject comes from one of them and is regularly reported as though it came from all. Among the 11,696 drivers, 98 percent reported problems finding safe parking. Read the distribution behind that number and it becomes a different claim: 75 percent reported problems regularly, meaning one or more times a week, 20 percent occasionally, 3 percent rarely, and 2 percent never. The 98 percent is everyone except the never category. The regular share was 76 percent in the 2015 round and 75 percent in 2019, so on the measure that describes a weekly operational problem, nothing improved and nothing deteriorated.
The 2015 round separates its populations more carefully. Its stakeholder survey covered 391 truck stops and drew 249 responses from trucking firm management and logistics personnel, 820 from fleet drivers and 7,333 from independent drivers, and it reports the share experiencing regular problems as over three-quarters among drivers and nearly two-thirds among the management and logistics respondents. Those groups have different exposures, and collapsing them produces a figure belonging to neither.
State reporting has its own precision problem. In the 2015 report’s survey chapter, 36 state departments of transportation, given as 72 percent, answered affirmatively when asked whether their state had a truck parking problem. In the same report’s conclusions the figure is 37 and 72.5 percent. The chapter is part of the citation, because the report gives two answers.
The demand term counts the wrong trucks
The most useful thing in either report is FHWA’s own account of why the question resists a single number. The 2015 metrics chapter states that parking demand and supply are highly dynamic, that there is often a mismatch between a driver’s demand for parking at a particular point in space and time and the availability of an adequate space at that point and time, and that measuring adequacy therefore requires a full set of measures rather than one. More than 35 candidate metrics came out of a workshop convened for the purpose. FHWA then derived a separate three-tier system, graded by whether the data is easily obtainable, requires surveys and purchases, or does not exist at national scale.
What got reported was narrower. The 2015 metrics counted facilities and spaces, the ratio of private to public spaces, spaces against state gross domestic product, spaces per 100,000 truck vehicle miles traveled, and spaces per 100 miles of the National Highway System. The 2019 round added parking near nationally significant origins and destinations, spaces within five miles of the National Highway Freight Network and per 100 miles of it, and spaces within one mile of an Interstate.
Every one of those is a supply measure normalised by mileage, travel, geography or economic output. The recommended first tier does carry one demand row, truck travel on the National Highway System, drawn from performance monitoring and the Freight Analysis Framework. It counts trucks passing a point, not trucks that wanted to stop at one. Nothing in either list carries a term for how many trucks need to stop at a given hour in a given place. That is not a criticism of the analysts. It describes what data exists, and it is why the shortage is easier to demonstrate than to size.
Where the reports get concrete is in observed displacement. In 2015, 24 states reported seeing trucks parked along freeway interchange ramps, 23 along freeway shoulders, 18 on conventional highway roadsides and 12 on local streets. Unofficial parking is a proxy for demand rather than supply, which makes it the most direct evidence in the file.
The clock that generates the demand
The timing is so sharp because it is written into the hours-of-service rule. Under 49 CFR 395.3 a property-carrying driver may not drive without first taking 10 consecutive hours off duty, may not drive after a period of 14 consecutive hours following the start of duty, may drive a total of 11 hours inside that window, and may not drive once more than 8 hours of driving time have passed without a consecutive 30-minute interruption in driving status.
The 14-hour window is the operative constraint, because it runs on the clock rather than on driving. Time spent looking for a space is inside it. That is why both surveys find demand in the same band: the 2019 round names 4 PM to 5 AM, Monday through Thursday, October through February, and the 2015 round found weekday demand higher than weekend and overnight demand higher than daylight. The regulatory clock, not traffic, sets the peak. The crash consequences are covered in commercial truck safety on the Interstate.
Who is building, and who is required to plan
Nearly nine spaces in ten are private, and the private operators surveyed in 2019 describe a sector with no plans to expand. Their facilities average 143 spaces, with 100 to 300 common, and they report operating over 100 percent capacity overnight, on weekdays and from May to October. Yet 79 percent have no plans to add truck parking, and roughly three-quarters each do not monitor their parking at all, do not offer reservations and do not charge for it. Capacity that is free, unmonitored and unreservable cannot be allocated, and an operator earning nothing per space has no revenue case for building the next one. Nearly nine tenths of it sits outside the planning instruments behind freight infrastructure coverage.
The federal position was restated on June 27, 2025 in a joint FHWA and FMCSA memorandum from Martin C. Knopp and Philip W. Thomas, replacing 2022 guidance. It notes an executive order signed on April 28, 2025 directing the department to develop an action plan on truck driver working conditions, and states that trucks move over 73 percent of the nation’s goods by value and over 67 percent by weight. That weight share sits slightly above the tonnage share the Freight Analysis Framework publishes for its 2017 base year, a reminder that the two come from different tabulations, as freight corridor measurement sets out.
The memorandum’s substantive content is eligibility, and the seven project types qualifying under section 1401(b) of MAP-21 cover more ground than most discussion of the subject assumes: safety rest areas, parking beside truck stops and travel plazas, opening weigh stations and park-and-ride lots to trucks, publicising existing capacity through intelligent transportation systems, turnouts, capital work to keep seasonal facilities open year-round, and improved interchange geometry to reach parking. Turnouts must meet the standards incorporated by reference at 23 CFR Part 625, which is where parking meets the design rules in how trucking shapes highway design.
The structural change is quieter. The 2021 infrastructure law amended 49 U.S.C. 70202 so that state freight plans updated after November 15, 2021 must carry a commercial motor vehicle parking facilities assessment, and section 70202(f) specifies its content: the capability of the state together with its private sector to provide adequate parking and rest facilities, the volume of commercial motor vehicle traffic in the state, and whether any areas have a shortage, including an analysis of its underlying causes.
That is the first federal requirement that anyone produce a causal account rather than a count, and the honest reading of what exists today is narrower than the advocacy around it. The country knows roughly how many spaces there are, knows they sit in small private facilities that fill on winter weeknights, knows drivers are displaced onto ramps and shoulders in at least two dozen states, and has never measured how many trucks wanted to stop and could not. Until one state freight plan reports that number for one corridor, the size of the shortage remains an inference.