Speed limit reduction expanded on I-15 through Helena
HELENA, Mont. - The 65 miles per hour speed zone on Interstate 15 has been expanded to begin half a mile south of the South Hills Interchange at exit 190, according to the Montana Department of Transportation (MDT).
"This change is in response to the new urban area boundaries approved by the Federal Highway Administration," MDT said. "In accordance with Montana Law (MCA 61-8-303 (a)), interstate speed limits must be reduced to 65 mph in urban areas with populations over 50,000. The population within the new boundary exceeds this threshold."
The Montana Transportation Commission approved the change in December 2025.
MDT said any local residents with questions or comments about the speed limit reduction is encouraged to contact MDT Traffic and Safety Engineer Gabe Priebe at 406-444-9252 or Lead Investigations Engineer Brenden Borges at 406-444-6255.
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