I certainly see your points. As far as the North having a "railroad network" I don't agree.
Here is an excerpt of an 1836 tallying of railway deveopment to date:
RAILWAYS COMPLETED OR PROGRESSING IN 1836.
In H. S. Tanner's American Traveler or Guide Through the United States, published in Philadelphia in 1836, the favorite routes of travel of that era are described at length, and the following list of railways then completed, or in course of construction, is given under the heads of the different states, viz.:
ALABAMA.A railroad is now in progress from Decatur, in Morgan county, to a point 10 miles below Tuscumbia, on the Tennessee. Length, 62 miles.
DELAWARE.The New Castle and Frenchtown Railroad extends from New Castle to Frenchtown. Length, 16 and 19/100 miles. A railroad to extend from Wilmington to Downingtown, in Pennsylvania, is proposed.
GEORGIA.Alatamaha and Brunswick Railroad, 12 miles in length.
KENTUCKY.Lexington and Ohio Railroad, commences at Lexington, passes through Frankfort, and thence to shipping point, near Louisville. Length, 85 miles.
LOUISIANA.The New Orleans and Pontchartrain Railroad, 5 miles long.
MARYLAND.Baltimore and Ohio Railroad, extends from Baltimore to Point of Rocks, on the Potomac, 67-five-eighths miles from Baltimore. This road is to be continued to the Ohio river. A road of a single track extends from the main line to Frederick, 3½ miles. Baltimore and Susquehanna Railroad, commenced in 1830, is to extend to York, Pennsylvania. Length, when completed, 76 miles. Another railroad is projected, to extend from Baltimore to the Susquehanna at Port Deposit, and thence to unite with the Oxford Railroad, of Pennsylvania, which intersects the Columbia Railroad about 40 miles from Philadelphia. Baltimore and Washington Railroad. Length, 37¾ miles. This work is now completed.
MASSACHUSETTS.Worcester Railroad, 43 miles in length. It is proposed to continue this road to the Connecticut, and to construct a branch to Milberry. Boston and Providence Railroad. Length, 43 miles. Boston and Lowell Railroad, length 25 miles, now in progress. Quincy Railroad, used for transporting granite from the quarry in Quincy to Neponset river. Length, 3 miles; branches, 1 mile.
MISSISSIPPI.St. Francisville and Woodville Railroad, 26 miles in length. Vicksburg and Clinton Railroad, length 37 miles (proposed).
NEW JERSEY.Camden and Amboy Railroad, commences at Camden, opposite Philadelphia, and terminates at South Amboy. Length, 61 miles. Paterson and Hudson River Railroad, from Jersey City, opposite New York, to Paterson, on the Passaic. Length, 16 30/100 miles. It is proposed to extend this road to the Morris Canal. New Jersey Railroad, commences on the last-mentioned railroad, about 2 miles from Jersey City, and terminates at New Brunswick. Length, 28 miles.
NEW YORK.Mohawk and Hudson River Railroad, from Albany to Schenectady, 16 miles. Schenectady and Saratoga Railroad, from Schenectady to Saratoga Springs, 20 miles. Catskill and Canajoharie Railroad, from Catskill to Canajoharie (now in progress), 70 miles. Ithaca and Owego Railroad, 29 miles. Harlem Railroad, on Manhattan Island. Rochester Railroad (now in progress), from Rochester to a point below the Falls of Genesee, Schenectady and Utica Railroad (now in progress). Length, 80 miles. Bath Railroad, from Bath to Crooked Lake, 5 miles. Rochester and Batavia Railroad (now in progress), 28 miles. Troy and Ballston Railroad (now in progress), 22 miles. Several other roads are proposed in different parts of the state.
NORTH CAROLINA.Railroads are projected to extend from Fayetteville to Cape Fear river; from Wilmington, through Fayetteville and Salisbury, to Beattysford, on the Catawba, a distance of 250 miles; and several others.
PENNSYLVANIA.State Railroads.Columbia Railroad, extends from Philadelphia to Columbia, on the Susquehanna. Length, 81 60/100 miles. Allegheny Portage Railroad, from Hollidaysburg to Johnstown, forms the connecting link between the Central and Western divisions of the Pennsylvania Canal. Length, 36 69/100 miles. Railroads constructed by joint stock companies:
Mauch Chunk Railroad, from Mauch Chunk to the coal mines, 9 miles. Room Run Railroad, from Mauch Chunk to the coal mine on Room Run,5 26/100 miles. Mount Carbon Railroad, from Mount Carbon to Norwegian valley, 7 24/100 miles. Schuylkill Valley Railroad, from Port Carbon to Tuscarora, 10 miles; branches of the preceding, 15 miles. Schuylkill Railroad, 13 miles. Mill Creek Railroad, from Port Carbon to the mines near Mill Creek, Length, including branches, 7 miles. Mine Hill and Schuylkill Haven Railroad, from Schuylkill Haven to the coal mines at Mine Hill. Length, including two branches, 20 miles. Pine Grove Railroad, 4 miles in length. Little Schuylkill Railroad, from Port Clinton to Tamaqua, 23 miles. Lackawaxen Railroad, from Honesdale to Carbondale, 16½ miles. West Chester Railroad, front the Columbia Railroad to West Chester, 9 miles. Philadelphia, Germantown and Norristown Railroad, (about 7 miles of this road are completed; a new route to Norristown, leaving Germantown to the north-east has been adopted.) Lykens Valley Railroad, front Broad Mountain to Millersburg. Philadelphia and Trenton Railroad, 26¼ miles in length. Central Railroad, from the vicinity of Pottsville to Sunbury, 44 54/100 miles; Danville branch, 7 miles long; whole length 51 54/100 miles. Oxford Railroad, now in progress, extends from the Columbia Railroad to the Maryland state line. Reading Railroad, to extend from Norristown to Port Clinton.
RHODE ISLAND.Stonington railroad, now in progress, extends from Stonington, in Connecticut, to Providence, 46 miles in length. A company has been incorporated to construct a railroad from Providence to Norwich, in Connecticut.
SOUTH CAROLINA.South Carolina Railroad, commences at Charleston, and terminates in the town of Hamburg, opposite Augusta; entire length, 135 75/100 miles. It is proposed to construct a branch to Orangeburg, and thence to Columbia, &c., and another to Barnwell Court House.
TENNESSEE.A railroad from the town of Randolph, on the Mississippi, to Jackson, in Madison county, 65 miles, and one from Nashville to New Orleans, are proposed, and measures for insuring their early completion have been adopted.
VIRGINIA.Manchester Railroad, extends from Manchester to the coal mines. Length, 13 miles. Winchester Railroad, extends front Harper's Ferry to Winchester. Length, 30 miles. Petersburg and Roanoke Railroad, extends from Petersburg, in Virginia, to Blakely, at the foot of the Roanoke Canal, in North Carolina. Length, 59 38/100 miles. A branch of this road leaves the main line about 10 miles from Blakely, which extends to the head of the rapids of Roanoke. Length, about 12 miles. Portsmouth and Roanoke Railroad, commences at Portsmouth, opposite Norfolk, passes in it direct course, intersects the Petersburg road 6 miles from Blakely, and terminates in the Roanoke a short distance below the Petersburg branch. Length, 80 miles. Richmond and Petersburg Railroad (now in progress) Length, 21 50/100 miles. Richmond and Fredericksburg Railroad (now in progress). Length, 64 miles. Belleplain Railroad, extends from Fredericksburg to Belleplain, situated on a branch of the Potomac (in progress). Length, 11 miles. Several other railroads are proposed.
The reported number of miles of railway constructed in the United States in the third decade was 2,264.67. Of this mileage, the amount completed in each of the years named was as follows: 1830, 39.80; 1831, 98.70; 1832, 191.30; 1833, 115.91; 1834, 213.92; 1835, 137.82; 1836, 280.08; 1837, 348.38; 1838, 452.88; 1839, 385.88; total, 2,264.67.
Of these railways, the mileage located in New England was 356.68; in Middle states, Delaware, Maryland, and a few Western and Northwestern states, 1,399.89; Southern states, 487.35; South-western states, 20.75.
Don't see much of a "network" in the above information. These railroads are all very short, more like segments.
This image is of a 19th Century model of an American 1840 engine, and supposedly from real life.
This is labled 1854-58, English, and very much later than the time we are discussing. The English machines were larger and heavier than American at this time.
Somewhere I saw an drawing of railroad rails through time. The 1840 rails were tiny, just 2, 2.5 inches high, and so fully stressed by the miniature engines of the day and six cars carrying a dozen passengers each.
What I am getting at is that the 1840 railroad technology was capable, over 1861-65 time and distance, of miniscule tonnage.
In any case the Northern manpower and industrial capability were too small to force a decision in 1840, I think. Ironclad invulnerable warships, Dahlgren guns, Parrott rifles, etc. were in the future. I doubt even a blockade of the South was possible.
More importantly the indoctrination of the Northern population was not far enough advanced in 1840. The extremely violent North of 1863 was just not there in 1840. Politically there wasn't any readiness for an invasion of the South. As Clausewitz put it, "War is an extension of politics..."
An 1840 War of Secession would, I believe, have been something more the Blackhawk War than "Mr. Polk's War", much less like 1861-65. Had a good time working this post up. Bit of an historical bent myself!