Perhaps fitting in light of the increasingly poor condition of the nation’s roads, more vehicles were removed from American highways and byways in fourth-quarter 2010 than in any quarter since the “Cash for Clunkers” program ended in August 2009, Experian Automotive research reveals.

Experian data indicate 1.2 million-plus cars and trucks were carted off to junk yards in October-December as the number of licensed vehicles reached 239,811,984 at year-end, up a modest 750,041 units from those tallied 12 months earlier.

Vehicles in the ’83 through ’92 model years figured prominently in the scrappage count.

The number of licensed vehicles in that age range fell 8.3% in the final six months of 2010, when a total 5.7 million hit the crusher, the research notes.

At the same time, the average age of cars and trucks on the road increased 3.3% to 9.9 years in fourth-quarter 2010, compared with 9.6 years in like-2009.

Given the still-modest pace of new-vehicles sales and the rapidly aging fleet, growth in the overall U.S. vehicle parc is expected to remain low in 2011.

The latest registration count compiled from state data by the Federal Highway Admin. for 2009 indicates the size of the U.S. car and truck fleet fell by more than 1.9 million units, or 0.8%, to 249,129,048 from the record 251,046,819 counted in 2008.

Related document: U.S. Total Vehicle Registrations by State, 2005-2009

The sharp decline followed a modest gain of just 672,000 units (0.3%), in 2008, after increases of 3.6 million (1.5%), in 2007 and 2.7 million (1.1%), in 2006.

Following a 0.4% decline the prior year, the number of registered trucks increased by more than 432,000 in 2009 from 2008 but fell shy of 2007’s record 112,851,260, while more than 2.0 million cars were taken off the roads in 2009.

This marked the first decline in 18 years, since the number of cars and trucks on the road in 1990 shrank 0.3% to 187,505,190 from 188,028,475 the prior year.

That shortfall was due to a 981,000-unit dip in the number of registered cars that partially was offset by an increase of 457,000 in the number of licensed trucks.

Motorcycle registrations, on the other hand, rose once again in 2009, despite lower fuel prices, albeit at a more modest pace than in the prior year, when $5 per gallon gasoline prompted a significant increase. The deepening economic recession was credited with boosting the motorcycle count even as fuel prices moderated significantly.

According to FHWA data, the number of registered “bikes” increased 2.7% in 2009 to 8,127,098, from 7,912,051 in 2008, when a surge in fuel prices prompted a spike of more than 620,000, or 8.5%, in the number of “2-wheelers” on the roads.

But despite the increase of motorcycle registrations, the total number of motor vehicles on U.S. roads – cars, trucks, buses and motorcycles – fell to 258,098,183 in 2009 from prior-year’s record 259,802,562.

Still, the size of the fleet remained at a near-record level and slightly ahead of third-ranked 2007’s 258,501,422 units.

A Ward’s analysis of FHWA car and truck data shows five of nine regions had fewer cars and trucks operating in 2009 compared with the preceding year, a reversal from 2008 when just three regions registered fewer units.

Related document: U.S. Total Vehicle Registrations by Region, 2005-2009

Collectively, those five regions saw 2,427,399 cars and trucks removed from registration rolls in 2009 compared with an increase of 500,911 in 2008.

Areas along the East Coast suffered the largest losses, while the western part of the country added to the vehicle population.

The South Atlantic, home to the country’s largest regional vehicle count, suffered the greatest loss in 2009, with nearly 1.7 million units dropped from the rolls. That equaled a 3.4% decline to 46,576,440 cars and trucks from the record 48,264,206 units registered in 2008 and a 4-year low, barely ahead of the 46,322,949 tallied in 2005.

The decline included nearly 1.1 million cars and more than 600,000 trucks with Florida, alone, the third-largest state in vehicle registrations, down by more than 1.1 million units.

At the same time, the Mid-Atlantic region lost nearly a half-million cars and trucks in 2009, dropping to 27,087965 units, also a 4-year low, from 27,566,197 in 2008, while the New England region declined by 139,268 to 11,915,806 – a 7-year low.

Economically hard-hit by the recession’s toll on manufacturing jobs, the East North Central region, encompassing Illinois, Indiana, Michigan, Ohio and Wisconsin, surprisingly lost few vehicles in 2009. The previous year, more vehicles were added to the roads there than in any other region.

Registrations declined by just 15,097 units in the ENC to 39,363,208 from 39,378,305 in 2008, but that still was the area’s second-highest count ever.

Wisconsin showed the largest drop within the ENC, down 125,270 vehicles, followed by much smaller declines in Indiana and Michigan. However, the addition of more than 185,000 units made roads in Illinois and Ohio a bit more crowded in 2009.

The Pacific region, second only to the South Atlantic in the number of vehicles on its roads, added the most units in 2009, upping its count by 445,713 to a record 44,555,330 from prior-year’s then-record 44,109,617.

Despite economic woes, California’s vehicle population, the largest of any state, grew by a whopping 950,000-plus units in 2009. That included a surprising 1.0 million-plus light trucks in arguably the country’s most environmentally conscious state.

Californians also put some 53,000 more cars on state roads in 2009, but the number of medium- and heavy-duty trucks fell by more than 118,000. However, the state’s gain largely was offset by declines elsewhere in the region, including a 50,000-unit cut in Hawaii.

Registrations in the Mountain region remained virtually the same in 2009 as in 2008, with a falloff of just 3,500 units.

Ironically, the state that was home to the region’s smallest vehicle fleet, Wyoming, posted the largest decline totaling some 59,000 units, or 8.3%. The drop there, as well as those in Arizona, Colorado and Nevada, nearly were all offset by gains in Idaho, New Mexico and Utah.

abinder@wardsauto.com