Yes, it halted completely. No cars, commercial trucks, or auto parts were made from February 1942 to October 1945.

On January 1, 1942, all sales of cars, as well as the delivery of cars to customers who had previously contracted for them, were frozen by the government’s Office of Production Management. As a temporary measure, local rationing boards could issue permits allowing persons who had contracted for cars before January 1st to secure delivery.

President Roosevelt established the War Production Board on January 16, 1942. It superseded the Office of Production Management. The WPB regulated the industrial production and allocation of war materiel and fuel. That included coordinating heavy manufacturing, and the rationing of vital materials, such as metals, rubber, and oil. It also established wage and price controls.

All manufacturers ended their production of automobiles on February 22, 1942. The January 1942 production quota had been a little over 100,000 automobiles and light trucks. The units manufactured at the beginning of February would bring up the total number of vehicles in a newly established car stockpile to 520,000. These would be available during the duration of the war for rationed sales by auto dealers to purchasers deemed “essential drivers.”

Representatives from the auto industry formed the Automotive Council for War Production in April 1942, to facilitate the sharing of resources, expertise, and manpower in defense production contracting.

The auto industry retooled to manufacture tanks, trucks, jeeps, airplanes, bombs, torpedoes, steel helmets, and ammunition under massive contracts issued by the government. Beginning immediately after the production of automobiles ceased, entire factories were upended almost overnight. Huge manufacturing machines were jack hammered out of their foundations and new ones brought in to replace them. Conveyors were stripped away and rebuilt, electrical wires were bundled together and stored in the vast factory ceilings, half-finished parts were sent to steel mills to be re-melted, and even many of the dies that had been used in the fabrication of auto parts were sent to salvage.

The government’s Office of Price Administration imposed rationing of gasoline and tires and set a national speed limit of 35 mph.

By April 1944, only 30,000 new cars out of the initial stockpile were left. Almost all were 1942 models and customers required a permit to make the purchase. The Office of Price Administration set the price. The government contemplated rationing used car sales as well, but that was finally deemed unnecessary. The government estimated that about a million cars had been taken off the road by their owners, to reserve for their own use after the war.

In the autumn of 1944, looking then toward the end of the war, Ford, Chrysler, Nash, and Fisher Body of General Motors received authorization from the War Production Board to do preliminary work on experimental models of civilian passenger cars, on condition that it not interfere with war work and that employees so used be limited to planning engineers and technicians. Limits were also set on the amount of labor and materials the companies could divert to this.

During the war, the automobile and oil companies continued to advertise heavily to insure that the public did not forget their brand names. Companies also were proud to proclaim their patriotic role in war production, and their advertisements displayed the trucks, aircraft, and munitions that they were making to do their part in combat.

In addition, auto advertisements encouraged the public to patronize local auto dealers’ service departments so that car repairs could help extend the lives of the cars their customers had bought before the war. In the last couple of years of the war, the auto companies also used their advertisements to heighten public anticipation of the end of the war and the resumption of car and truck manufacturing, with advertising copy such as Ford’s “There’s a Ford in Your Future.”

The period during which Frémont's chart appeared was one of rapid industrialization and urbanization in the Northeastern states. Economic historian Douglass C. North has identified the 1840s and early 1850s as the era in which "the pace of industrialization accelerated to the degree that the Northeast could unequivocally be called a manufacturing region."

In 1850, urban population in the Northeast accounted for 27 percent of the total population, while the South was only eight percent urban. During the next decade, the South remained predominately rural, with 10 percent of its population living in cities or towns in 1860, while the Northeast continued to urbanize at a swift pace, with an urban population that had grown to 36 percent. Despite the region's growth in industry and urban population, the Northeast retained a large rural population: 73 percent of its total population in 1850 and 64 percent in 1860. Yet, the size of the rural Northeastern population accounts only for part of the answer to the apparent contradiction stated in the question. The seeming paradox can be only resolved if we start by noting the exact language that was used in Frémont's chart.

The chart explicitly referred to "free states," not states in the North or Northeast. During this period, the number of farms in the developing area that we now call the Midwest—which with the exception of Missouri was composed solely of free state—increased at a faster pace than in any other region of the nation due to the increasing ability of persons of modest means to purchase newly available, relatively small plots of public land. These new farms tended more and more to be oriented to the market rather than to self-sufficiency. The concurrent rise in urban population in the Northeast was closely related to the growth of agriculture as a commercial enterprise in the Midwest. As cities grew, so did a demand for food that Midwestern farmers supplied. A closer look at the statistics and at the analyses of agricultural and economic historians will help make further sense of the situation.

The number of farms listed on Frémont's chart was derived from the 1850 census (with one small discrepancy—while the chart lists 873,678 farms in free states, the total calculated from the census actually comes to 873,608). According to census figures, New England states (Maine, Vermont, New Hampshire, Massachusetts, Rhode Island, and Connecticut) accounted for 19 percent of the farms in free states, or 167,651 farms; Middle Atlantic free states (New York, Pennsylvania, and New Jersey) totaled 37 percent or 322,103 farms; and the Midwestern free states (Ohio, Indiana, Illinois, Michigan, Wisconsin, and Iowa) 44 percent or 382,982. (The census listed only 872 farms in California, the only state in the far west that had been admitted to the Union by that time.) New York led the free states in number of farms with 170,621. Ohio, the first Midwestern state to be settled, came in second with 143,807. Pennsylvania followed with 127,577, Indiana had 93,896, and Illinois 76,208. In the slave states, Virginia had the most farms with 77,013, followed by Kentucky with 74,777, Tennessee with 72,735, North Carolina with 56,963, Missouri with 54,458, and Georgia with 51,759.

During the decade of the 1850s, the total number of farms in the U.S. increased by 41 percent, from 1,442,908 to 2,030,785 farms. Nearly half of the new farms were located in the free states of the Midwest. In his classic work of U.S. agricultural history, The Farmer's Age: Agriculture, 1815–1860, Paul W. Gates stated that the "rush for the public domain" during the 1850s "surpassed anything in previous history." Gates attributed the rise in land sales to lower prices and to "[f]rantic railroad building, particularly in the upper Mississippi Valley; the great influx of Germans, Scandinavians, and Easterners into the West; and a new era of banking experiments which greatly increased available credit." Historians have identified this period as part of an "agricultural revolution" that eventually led to the passage of the Homestead Act of 1862, through which homesteading settlers could obtain 160 acres of public land free of charge.

The revolution, which encouraged land speculators in addition to settlers, marked a major shift in agricultural practice in the free states, as "by the 1850s, market-oriented agriculture was firmly established as the dominant approach, clearly distinguishable from the semisubsistence approach," according to agricultural historian Clarence H. Danhof. Economic historian Harold D. Woodman has characterized the "large class of property owners on western lands" during this period as consisting "neither of peasant proprietors nor of yeoman farmers but, rather, of businessmen on the make."

Two visions of the nation's future had dominated early legislative initiatives regarding land sales from the federal government, which under the Articles of Confederation had acquired all state-owned lands west of the Appalachians. Alexander Hamilton and his Federalist followers believed that prices for public land should be set at high levels both to benefit the U.S. treasury and to discourage agriculture in favor of manufacturing endeavors. In contrast, Thomas Jefferson and like-minded politicians, who envisioned a republic of yeoman family farmers, sought low prices for small lots of land that could be purchased on credit by people of average means.

Federalist policy prevailed in early land sales legislation; in 1790, the minimum cost for land purchased from the government was set at $1,280 and the minimum amount sold was set at 640 acres. Due to poor sales, later legislation gradually relaxed maximum and minimum terms, so that by 1820, the minimum price of an acre had dropped from a high of $2 to $1.25 and the minimum amount that could be sold was lowered to 80 acres. In 1832, this amount was reduced further to 40 acres, and by 1854, the minimum price for public land that had remained unsold for more than 30 years was lowered drastically to 12 ½ cents per acre.

The federal government sold nearly 50 million acres between 1850 and 1859. In free states, the number of farms increased by 44 percent to 1,255,518 farms, while those in the slave states increased by 36 percent to 775,267. Midwestern states experienced the highest growth rate in numbers of farms among all regions of the nation. Between 1850 and 1860, the number of farms in the New England states increased by 10 percent, with 16,291 new farms bringing the total to 183,942. Middle Atlantic states increased its number of farms by 18 percent with an additional 58,890 to total 380,993 farms.

Midwestern states (including Minnesota, which had become a state in 1858) increased their number of farms by 74 percent with an additional 283,079 farms to total 666,061, or 53 percent of free state farms. New York, Ohio, and Pennsylvania remained the states with the largest number of farms in the free states (196,990, 179,889, and 156,357, respectively), while Illinois had jumped to fourth place with 143,310 and Indiana increased to 131,826.

The far western states of California and Oregon (admitted to the Union in 1859) with 24,522 farms, accounted for 2 percent of the total number of farms in the free states. The number of farms in southern states in which public lands were sold increased dramatically: by 26 percent in Mississippi, 29 percent in Louisiana, 31 percent in Alabama, 53 percent in Florida, 70 percent in Missouri, 120 percent in Arkansas, and 252 percent in Texas. While the number of farms in the South grew at a greater rate than that of the Northeast, they increased by less than half the rate of Midwestern farms.

While the number of farms in the South was less than that of the Northeast and the Midwest combined, the size of farms in slave states was greater on average than those in free states. In 1850, the average-sized farm in the slave states was 318 acres; in the free states, the average size was 128 acres, or 40 percent of the size of an averaged-sized farm in the South. The average size of farms in both free and slave states remained near constant from 1850 to 1860. According to the 1860 census, an average-sized farm in the free states in 1860 was 125 acres, or 3 acres smaller than in 1850, while in the slave states the average acreage had increased from 318 to 319.

Frémont's Midwestern supporters, who put together the chart, were part of a growing movement of farmers who "broke politically with southern planters in the 1850s," according to agriculture and economics professor Willard W. Cochrane. These farmers, Cochrane has written, "came to resist the extension of slavery and the plantation system out of fear of competition from large plantation units based on slave labor with their small family-sized units." In order to survive during the transition to market-oriented farming, they allied themselves more with economic interests in the Northeast than with planters in the South. "The stage was thus set for the realignment of political power, the founding of the Republican party, and the eventual War between the States," Cochrane concluded.

There were two technological innovations that profoundly changed daily life in the 19th century. They were both “motive powers”: steam and electricity. According to some, the development and application of steam engines and electricity to various tasks such as transportation and the telegraph, affected human life by increasing and multiplying the mechanical power of human or animal strength or the power of simple tools.

Those who lived through these technological changes, felt them to be much more than technological innovations. To them, these technologies seemed to erase the primeval boundaries of human experience, and to usher in a kind of Millennial era, a New Age, in which humankind had definitively broken its chains and was able, as it became proverbial to say, to “annihilate time and space.” Even the most important inventions of the 19th century that were not simply applications of steam or electrical power, such as the recording technologies of the photograph and the phonograph, contributed to this because they made the past available to the present and the present to the future.
The 1850 song, “Uncle Sam’s Farm,” written by Jesse Hutchinson, Jr., of the Hutchinson Family Singers, captured this sense that a unique historical rupture had occurred as a result of scientific and social progress:

Our fathers gave us liberty, but little did they dream
The grand results that pour along this mighty age of steam;
For our mountains, lakes and rivers are all a blaze of fire,
And we send our news by lightning on the telegraphic wires.

Apart from the technological inventions themselves, daily life in the 19th century was profoundly changed by the innovation of reorganizing work as a mechanical process, with humans as part of that process. This meant, in part, dividing up the work involved in manufacturing so that each single workman performed only one stage in the manufacturing process, which was previously broken into sequential parts. Before, individual workers typically guided the entire process of manufacturing from start to finish.

This change in work was the division or specialization of labor, and this “rationalization” (as it was conceived to be) of the manufacturing process occurred in many industries before and even quite apart from the introduction of new and more powerful machines into the process. This was an essential element of the industrialization that advanced throughout the 19th century. It made possible the mass production of goods, but it also required the tight reorganization of workers into a “workforce” that could be orchestrated in various ways in order to increase manufacturing efficiency. Individuals experienced this reorganization as conflict: From the viewpoint of individual workers, it was felt as bringing good and bad changes to their daily lives.

On the one hand, it threatened the integrity of the family because people were drawn away from home to work in factories and in dense urban areas. It threatened their individual autonomy because they were no longer masters of the work of their hands, but rather more like cogs in a large machine performing a limited set of functions, and not responsible for the whole.

On the other hand, it made it possible for more and more people to enjoy goods that only the wealthy would have been able to afford in earlier times or goods that had never been available to anyone no matter how wealthy. The rationalization of the manufacturing process broadened their experiences through varied work, travel, and education that would have been impossible before.