U.S. Route 400

Route and characteristics

The alignment of US 400 passes mostly through the southern half of Kansas, serving a mix of two‑lane rural stretches, four‑lane divided highways and shorter freeway sections through larger cities. Along its course the route is frequently concurrent with other U.S. and state highways, a common practice that creates continuous signed routes without building entirely new roadways. Road type and traffic volumes vary considerably between open prairie sections and urban corridors.

History and development

Established in 1994, US 400 was intended to unify several existing roads under a single signed designation to simplify wayfinding and support regional travel. Initially the route terminated in Garden City, Kansas (Garden City), but in 1996 it was extended west to Granada, Colorado, creating the present end‑to‑end alignment. The decision to assign the three‑digit number 400 deviates from typical numbering practice: three‑digit U.S. routes are usually spurs of a two‑digit parent, but there is no "US 0" parent under the AASHTO numbering guidelines, making US 400 an unusual example.

Uses and regional importance

US 400 serves multiple roles: it carries agricultural and commercial freight across a wide swath of the Plains, links regional population centers and connects local traffic to national corridors like I‑44. For communities along its course, the highway is a vital economic artery supporting freight, commuting and access to services. Seasonal variations in traffic and the presence of long freight movements are typical for the route.

Notable facts and travel notes

• The highway traverses three states and is maintained by the respective state departments of transportation.
• Signage frequently shows US 400 together with other U.S. routes where the roads overlap; drivers should watch route shields for concurrent numbers.
• Because its number does not follow the conventional parent–spur pattern, US 400 is often cited as an atypical case in discussions of U.S. highway numbering.

For maps, current intersection details and planned improvements consult state DOT resources and official route logs. Additional technical and historical information can be found through regional highway publications and state transportation archives (near Joplin, Missouri references and planning documents often include local project data).