MOMissouri Geography

One cattleman gave Missouri its Bootheel

Missouri's southern boundary runs along 36 degrees 30 minutes north, the line the Missouri Compromise made famous, except in the southeastern corner where it drops about 30 miles further south to 36 degrees and sticks out in a rectangle. That is the Bootheel, and it is there because of John Hardeman Walker, a cattleman at Little Prairie, now Caruthersville, who had no intention of waking up in Arkansas Territory. He lobbied the territorial delegation while the 1820 enabling act was being drafted, and the line was bent south around his holdings, following the St. Francis River and then running east to the Mississippi.

The Bootheel is the only part of the state in the Mississippi Alluvial Plain and it holds the lowest ground in Missouri, 230 feet where the St. Francis River crosses into Arkansas. It was cypress swamp until the Little River Drainage District cut roughly 960 miles of ditch and threw up close to 300 miles of levee between 1914 and 1928, an excavation the district reckons moved more earth than the Panama Canal. Cotton and rice grow there now on ground that was under water a century ago.

Eight neighbours, and two of the lines were fought over

Missouri touches Iowa, Illinois, Kentucky, Tennessee, Arkansas, Oklahoma, Kansas and Nebraska. Only Tennessee matches that count. The northern line produced the Honey War in 1839, when Missouri and Iowa read the 1816 Sullivan Line differently and disagreed by up to 13 miles over which set of rapids on the Des Moines River it referenced. A Missouri sheriff cut down three bee trees while collecting taxes in the disputed strip, both governors called out militia, roughly 1,200 men turned out, nobody fired a shot, and the Supreme Court settled it in 1849 broadly in Iowa's favour.

The northwestern corner was bought, not surveyed. Missouri originally stopped at a north-south line drawn through the mouth of the Kansas River. The Platte Purchase of 1836 acquired roughly 3,150 square miles from the Ioway, Sac and Fox nations and pushed the boundary west to the Missouri River, adding six counties and giving the state the squared-off shoulder above Kansas City. St. Joseph sits on land that was outside Missouri when the state was admitted in 1821.

Mountains older than almost anything you can stand on

Taum Sauk Mountain in Iron County, 1,772 feet, is the summit of the St. Francois Mountains. These are not folded like the Appalachians or thrust up like the Rockies. They are the eroded stumps of a volcanic field that erupted about 1.47 billion years ago, and by the time shallow Paleozoic seas washed over the region they were already ancient, standing above the water as an archipelago of granite and rhyolite islands. The surrounding dolomite was laid down around them.

Two places make this legible. At Elephant Rocks State Park near Graniteville, granite that weathered along its joint planes while still buried has been exposed as a train of rounded boulders, the largest about 27 feet tall. At Johnson's Shut-Ins the Black River hits the same hard igneous rock and is squeezed into a slot of chutes and potholes instead of spreading out as it does over softer ground upstream. Mina Sauk Falls, on the flank of Taum Sauk, drops 132 feet in stages and is the tallest in the state.

A state drilled full of holes

More than 7,500 caves have been surveyed in Missouri, second only to Tennessee, which is where the Cave State label comes from. The cause is the Ozark Plateau, a thick pile of dolomite and limestone that groundwater has been dissolving for millions of years. The surface shows the consequences: sinkholes, streams that vanish into the ground and reappear miles away, and springs that discharge like rivers.

Big Spring near Van Buren puts out on the order of 286 million gallons a day, among the largest single-outlet springs in the country, and Greer Spring and Alley Spring are not far behind. The Current and Jacks Fork rivers they feed became Ozark National Scenic Riverways in 1964, the first unit of the national park system created specifically to protect a wild river. Because these rivers are spring-fed rather than runoff-fed, they run cold and clear through droughts that dry out streams elsewhere in the state.

Where the ice stopped and the two great rivers meet

Pleistocene ice sheets pushed south to roughly the line of the modern Missouri River and went no further. North of that line lie the Dissected Till Plains: glacial till, thick loess bluffs along the river, and rolling farm country. South of it the Ozarks were never glaciated and have been eroding without interruption for a very long time, which is why the topography there is a maze of narrow ridges and steep hollows rather than smooth hills. The Osage Plains occupy the western edge, the eastern tail of the tallgrass prairie.

The Missouri River, at 2,341 miles the longest in North America, enters the state at Kansas City, swings east across it and joins the Mississippi about 15 miles north of downtown St. Louis at Columbia Bottom. Water from Montana and water from Pennsylvania pass that confluence within the same current. Missouri has no large natural lakes; the Lake of the Ozarks, formed in 1931 when Bagnell Dam closed the Osage River, compensates with roughly 1,150 miles of shoreline wrapped around drowned valleys.

Warsaw holds both records, and the ground still moves

Warsaw in Benton County, population under 2,500, owns each end of the Missouri temperature record. It fell to minus 40 F on 13 February 1905 and reached 118 F on 14 July 1954, the latter tied by Union on the same day. A 158-degree range inside one small town is the clearest illustration of what a continental interior with no moderating ocean or mountain wall does to a thermometer.

Under the Bootheel lies the New Madrid Seismic Zone. Three earthquakes estimated at magnitude 7.0 to 7.5 struck on 16 December 1811, 23 January 1812 and 7 February 1812. They were felt as far away as the eastern seaboard, sand blows erupted across the alluvial plain, land subsided badly enough to form Reelfoot Lake across the line in Tennessee, and uplift of the riverbed briefly made the Mississippi appear to run backwards. The zone still produces hundreds of small tremors a year, most of them too faint to notice.

Common questions about Missouri geography

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