With any vehicle over 20 years old, where it lived is often more important than how many miles it has. A 200,000-mile XJ from Arizona can be structurally cleaner than an 80,000-mile example from Michigan. Rust is the XJ's most common terminal diagnosis, and it's almost entirely a geography problem.
Here's what to expect, region by region.
These are the hardest-hit states for XJ rust. Road salt is applied heavily from November through March, and vehicles that spent any meaningful time here absorb it into every crevice. The floor pans are the first to go, the thin sheet metal under the carpet rusts from the inside out as salt water pools and sits. By the time it's visible from above, the damage below is often severe.
Rocker panels on Rust Belt XJs are frequently rotted through. The rear frame rail corners where the unibody wraps around to the hatch, a structural area, can be completely absent on high-mileage examples. If you're in these states and shopping locally, plan your inspection accordingly. Don't buy without getting underneath.
Not all Rust Belt XJs are beyond saving, but the math changes. Factor in floor pan replacement, rocker patch panels, and undercoating, add $1,500–$3,000 to any repair estimate you're doing in your head when walking around one.
Similar salt exposure to the Rust Belt with the added variable of coastal humidity and ocean air, which accelerates surface corrosion. Fender lip rust, tailgate rust, and door seam rust are common here even on vehicles that were otherwise maintained. XJs from Connecticut or New Jersey often show external rust on the body before the floor pans fail, the opposite pattern from Midwest examples.
Check the tailgate hinge areas particularly carefully on Northeast XJs. The lower liftgate corners rust from behind, and by the time it's visible from outside it's often progressed deeply.
These states use road salt but typically less aggressively than the Rust Belt. XJs from here are often in reasonable shape underneath but show more surface rust than Southern examples. The key areas to check are the same, floor pans, rockers, frame corners, but you'll typically find the damage less advanced at comparable mileage.
Appalachian-area XJs that were driven off-road in mountain environments may have additional undercarriage wear and splash damage. Ask what the vehicle was used for.
Little to no road salt. The biggest rust risk here is high humidity and standing water from rain. Floor pan rust in XJs from humid Gulf Coast areas can develop, especially if the windshield or sunroof seal ever failed and water sat in the interior. But overall, Southern XJs are significantly cleaner underneath than their northern counterparts.
Texas XJs are particularly sought after by buyers in northern states specifically because of their rust-free history. A clean Texas XJ commands a premium, and usually earns it.
Caution: XJs from flood-prone Gulf Coast areas (coastal Louisiana, parts of Houston) can have hidden water damage. Check for silt or sand deposits in the door sills and behind the rear interior panels.
These are the cleanest XJs on earth. Almost no moisture, no salt, minimal road treatment. XJs from Arizona or Nevada regularly show original factory undercoating in near-perfect condition even at very high mileage. The caveats: UV damage to interior plastics and exterior trim, and potential brake system issues from long dry periods between service.
Southwest XJs are worth chasing. If you're in a Rust Belt state, buying from Arizona and driving it home or having it shipped is a legitimate strategy for getting a solid foundation. The price will reflect it, but so will your peace of mind.
High rainfall and some salt use in mountain passes. XJs from the rainy parts of Oregon and Washington can show significant rust, particularly in the lower door seams and floor pans, because of the constant wet environment without a freeze/thaw cycle to dry them out. Seattle-area XJs can be surprisingly rusty for a state that doesn't use heavy salt.
Northern California is much better, lower rainfall, less humidity. Bay Area and Central Valley XJs tend to be in good shape.
A Rust Belt XJ that was undercoated annually and garage-kept can outlast a Southwest example that was neglected and abused. History and maintenance matter alongside geography. But when you're doing a blind search or buying sight-partially-seen, knowing where an XJ lived for most of its life gives you the best single indicator of what you'll find underneath it.
