Jo Daviess County. Our own 3DEP reading at the USGS point is 1,234 feet. The low point is 279 feet where the Ohio joins the Mississippi at Cairo, a Corps of Engineers figure in the USGS table
Against under 32 inches in the north. Snow runs the other way, 36 inches a year up north and under 10 in the far south
Service between Corps lakes
The federal camping in Illinois is Corps of Engineers camping: 23 of the 24 drive-in federal sites in the state, spread across Carlyle, Rend, Shelbyville and the river pools. That means hookups, dump stations and the ordinary rhythms of reservoir camping rather than boondocking, and it means most service needs are electrical, plumbing and slide-out rather than suspension.
Two Illinois specifics for a shop to raise. Camping on state ground is only ever in a designated campground, so tell customers not to plan on overnight lay-bys, and trailer and vehicle camps alike are capped at 40 feet overall on state property, which catches some long fifth-wheel and toy-hauler combinations.
A camper van, truck camper or expedition vehicle has two sets of systems, and most mechanics only want one of them. RV and van service centers work on the living side: the 12-volt system, heat, water, ventilation and everything that leaks or rattles loose after a season of dirt roads.
Typical work
01House battery, charging, solar and inverter diagnosis
02Diesel and propane heaters, and water heaters
03Plumbing, pumps, tanks and winterizing
04Roof fans, air conditioning, windows and seals
05Appliance service and leak repair
How to choose a service center
These systems are brand-specific, and so is the training.
01Ask which brands of heater, battery and inverter they are trained on.
02Ask if they will work on owner-built or small-builder vans. Some will not touch wiring they did not install.
03Ask about turnaround in season. Service backs up in spring and summer.
04Bring documentation: a wiring diagram, a component list and photos from the build.
What to have ready before you ask for a quote
Model numbers save a phone call.
01The vehicle or camper, and who built it
02The components: battery type and size, inverter, heater model
03What it is doing, and when
04Photos of the installation
05Where and when you can drop it off
Questions people ask
My heater stopped working at altitude. Is it broken?
Maybe not. Fuel-burning heaters can struggle at high elevation and may need an altitude setting or kit, and they soot up if they only ever run on low. A service center that knows the brand can check it and set it up for where you camp.
Can a shop add solar or lithium to an existing system?
Usually, but lithium batteries need compatible charging from the alternator, solar and shore power. A shop should look at the whole system rather than swap the battery and hope.
How do I winterize a van?
Drain or protect anything that holds water: tanks, pump, lines, water heater and filters. How you do that depends on how the system was built, so ask the builder or a service center to show you once.
How high is Illinois?
From Cairo at 313 feet to Charles Mound at 1,235.
Altitude decides what your engine, your brakes and your lungs have to work with, and how late in the year the passes open.
02,000
Feet above sea level
Towns
ShelbyvilleShelby County seat at Lake Shelbyville, six federal campgrounds and two state parks on one reservoir, with Hidden Springs State Forest ten miles southeast.646 ft
JonesboroUnion County seat. Mississippi Bluffs Ranger District office, Trail of Tears State Forest five miles northwest, and the LaRue Pine Hills loop starts here.570 ft
OquawkaHenderson County seat on the Mississippi. Big River State Forest and its 60 miles of firebreaks are eight miles north on the Oquawka to Keithsburg road.553 ft
WilmingtonOn State Route 53, the old Route 66 alignment, two miles south of the Midewin National Tallgrass Prairie headquarters and welcome centre.543 ft
Forest CityMason County village that is the headquarters address for Sand Ridge State Forest, the largest state forest in Illinois and its main backcountry camping.494 ft
BentonFranklin County seat off I-57. Rend Lake and its five public campgrounds sit west of town, with the Corps office on Rend City Road.473 ft
CarlyleOn US 50 fifty miles east of St. Louis at the largest lake in the state, with the Corps visitor centre on the shore and camping all round it.460 ft
MurphysboroJackson County seat on Route 149. Johnson Creek Recreation Area on Kinkaid Lake, one of four Shawnee campgrounds rated for a 40-foot rig, is northwest.419 ft
CarbondaleLargest town in southern Illinois and the working base for the western Shawnee. Giant City State Park is near town and the Mississippi Bluffs district office is south at Jonesboro.416 ft
ViennaJohnson County seat on Route 45. Hidden Springs Ranger District office, one of the forest’s two districts and the office that issues its own motor vehicle use map.412 ft
Carrier MillsAddress of the Sahara Woods site office and the nearest town to the only state-run off-highway vehicle trails in Illinois.395 ft
HarrisburgSaline County seat on US 45. Shawnee National Forest supervisor’s office is on Highway 145 south of town, the Garden of the Gods road leaves Route 145 for Route 34, and the state OHV park is five miles west.394 ft
Cave-in-RockOhio River village at the state park with the 55-foot cave. The free Cave-In-Rock Ferry crosses to Kentucky here, supported jointly by both states.375 ft
ElizabethtownHardin County seat on the Ohio River Scenic Byway, between the Garden of the Gods road and the river, with Tower Rock’s free campground east on Route 146.361 ft
GolcondaPope County seat on the Ohio River Scenic Byway, on the eastern side of the Shawnee in the Hidden Springs district.354 ft
CairoThe southern tip of Illinois where the Ohio meets the Mississippi at 279 feet, the state low point, and where the Illinois stretch of the Ohio River Scenic Byway ends.313 ft
Passes, high roads and summits
Charles MoundThe highest point in Illinois, in Jo Daviess County in the far northwest corner. Our own 3DEP reading at the USGS point is 1,234 feet1,235 ft
Williams HillPope County, high ground in the Shawnee Hills on the eastern side of the national forest. The figure is our own reading of the elevation surface at its map point, because no agency publishes one1,062 ft
Bald KnobUnion County, in the hills behind the Mississippi bluffs on the western side of the national forest. The figure is our own reading of the elevation surface at its map point, because no agency publishes one1,028 ft
Pass, road and summit elevations are the figures published by the agency that manages them. Town elevations are the town’s or county’s own
figure where it publishes an exact one; the rest are from the U.S. Geological Survey (3D Elevation Program at the place’s official coordinates),
retrieved September 18, 2026. Every source is listed at the foot of the page.
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