The western terminus of the highway is at an intersection with U.S. Route 98 (US 98) northwest of Wilmer, just shy of the Mississippi state line.

The route will eventually become part of US 98 west of Mobile to the Mississippi state line as a four-lane bypass of Semmes.

The route widens to five lanes at its intersection with SR 213 near its interchange with I-65 at exit 13.

[citation needed] SR 158 was extended from its previous western terminus at Newburn Road 12.16 miles (19.57 km) to US 98.

[3] It bypasses a stretch of US 98 ("Old 98"), colloquially known as "Bloody 98" by locals due to its high amount of traffic fatalities.