(The opinions expressed here are those of the author, a columnist for Reuters.)
By John Kemp
LONDON, Jan 17 (Reuters) - If America's long love affair with the motor car is not exactly over, it has certainly become less intense in the past decade.
Statistics compiled by the Federal Highway Administration (FHWA) reveal a remarkable turning point: for the first time since the introduction of the internal combustion engine, vehicle use is rising more slowly than the U.S. population.
Fuel consumption is unchanged since 2002, while the resident population has increased by more than 26 million (9 percent).
In 2012, U.S. motorists purchased 172 billion gallons of gasoline and diesel, the same as in 2002, even though the U.S. population had climbed from 288 million to 314 million in the meantime.
The recession, tougher fuel economy standards for cars and light trucks and the increased use of biofuels have all contributed to the reduction in fuel consumption compared with the long-term trend.
But Americans were driving their cars and trucks fewer miles even before the recession started. Driving patterns began to shift around 2004, which coincides with a sharp rise in crude oil and pump prices.
The total number of miles driven on U.S. roads peaked at 3.031 trillion in 2007, fell during the recession and then stabilised. It was still down at just 2.968 trillion in 2012, according to the FHWA.
However, driving on rural roads began falling much earlier, in 2002, and has declined consistently since then. Rural road use is down more than 13 percent over the past decade (Chart 1).
Driving on urban roads continued to rise until the recession and has since stabilised. But the overall picture is that the volume of driving has failed to match the rate of increase in the population (Chart 2).
Chart 1: http://link.reuters.com/wah26v
Chart 2: http://link.reuters.com/zah26v
Chart 3: http://link.reuters.com/ceh26v
Chart 4: http://link.reuters.com/feh26v
In addition to the changes in fuel economy standards and increased use of biofuels, important shifts are taking place in behaviour and contributing to a big shift in fuel consumption.
Behavioural change matters because it suggests that a structural shift is occurring in demand for road transport fuel, which is the most important end-use for crude oil.
The change in the United States may also be occurring in the other advanced economies such as Britain. If it proves enduring, it could also influence forecasts about vehicle use and fuel consumption in rapidly developing economies such as China, India and Brazil.
The precise reasons for the change are not clear. Data on fuel consumption, car ownership, miles travelled and commuting are based on fuel excise tax collections and roadside surveys, which are fully available only two years later, as well as travel trends and commuting surveys, which are conducted even less frequently.
Even so, it is possible to offer some conjectures about what could be driving the shift. The U.S. population is becoming more urban, which would account for the decline in rural driving and could also make the average journey to work and for other purposes shorter.
There is some evidence that the shift from the inner cities and inner suburbs to outer suburbs has slowed and may be partially reversing.
Americans are certainly commuting less to and from work, according to the government, perhaps as a result of more home-working and living nearer to their work place.
The population is also aging, which reduces the relative number of work-related journeys.
The amount of driving for family errands and for other social and recreational purposes also has been falling steeply since the 1990s; perhaps because the fabled family cross-country road trip is becoming less common.
And although the trend is too new to show up in the statistics yet, online shopping and other transactions over the Internet could be reducing the number of trips that consumers make to stores.
On the business side, retailers and distribution companies are all looking to increase the efficiency of road haulage by better route-planning and making more use of distribution hubs to cut greenhouse gas emissions and reduce fuel bills. ("Better route planning cuts fuel use in freight sector", March 25, 2014, )
Data from the decennial censuses in 2000 and 2010 hints at demographic changes that are likely to affect driving behaviour.
The U.S. population is becoming more urban and suburban. In 2000, 6.7 percent of the population lived in rural counties. By 2010, the rural population had fallen to just 6.3 percent, according to the Census Bureau. ("Patterns of Metropolitan and Micropolitan Population Change 2000-2010", Sept 2012)
The federal government defines as a metropolitan area any county containing an urban area with a population of at least 50,000. Micropolitan areas include any county with a cluster of at least 10,000. Neighbouring counties may be included in a metropolitan or micropolitan area if they are closely integrated with the urban core. Rural counties are any that are not included in one of these core-based statistical areas.
In 2010, there were 366 metropolitan areas and 576 micro areas, according to the Census Bureau. Between the 2000 and 2010 censuses, the U.S. population increased by 27.3 million. But the increase was heavily skewed to metropolitan areas (25.2 million). The population of micro areas grew just 1.7 million and rural county populations were up by only 350,000.
The most rapid growth took place in metro and micro areas with a total population of between 100,000 and 5 million. Large metro areas (though not the very largest with over 5 million inhabitants) tended to grow faster than smaller metro areas, micro areas and rural counties.
The population continued to shift to the suburbs. Within metro areas, outlying counties tended to grow faster than the core. But the race to the outer suburbs may have slowed slightly. The biggest recorded increase was in the population living five to 15 miles from city hall (Charts 3 and 4).
The population is also clearly getting older. The median U.S. age rose from 35.3 in 2010 to 37.2 years in 2010. But in micro areas the median age rose from 36.7 to 39.3 years, and in rural areas it went up from 38.5 years to 41.9 years. Older residents are less likely to commute or undertake long journeys for work.
There are hints about changes in driving behaviour in the National Household Travel Survey (NHTS) too. Unfortunately the last survey was conducted in 2009, and the next one is not due until 2015. But the survey does suggest driving peaked in the 1990s and began to fall in the 2000s.
Between 1969 and 1995, the average number of miles travelled per person per day doubled from 20 to 39. The average number of journeys more than doubled from 2 to 4.3, though the length fell marginally.
But the average number of miles travelled per person per day fell in 2001 and again in 2009, to 36.9 and 36.1 respectively. The average number of journeys per day has also fallen to around 3.75 per person.
Typical commuting distances have lengthened slightly since the 1990s (though the distance may have peaked in 2001). But the average number of commutes per year has fallen around a fifth. Crucially, the number of commutes was falling even before the recession, perhaps because of increased home-working.
Trips for shopping and other errands have also fallen, by 7 percent and 25 percent respectively. For recreation and social purposes, the number of trips is up since the first half of the 1990s, but the average length has fallen by a quarter.
The mosaic of data on driving behaviour from different sources is too fragmented and too delayed to provide a clear picture about what has happened to driving patterns over the past decade. But most of it points to the fact that Americans are using their cars less than they did in the 1990s.
Something similar appears to be happening in the United Kingdom, where the distance travelled per person per year has stabilised and tapered slightly since about 2004, according to Britain's Department of Transport, which suggests the forces at work are not confined to the United States.
If these shifts prove enduring, and that's still a big "if", the consequences for future oil demand could be profound. (editing by Jane Baird)