Welcome to the official website of
Highway District No. 4
Our Purpose and Organization
Highway District No. 4 (HD4) is one of four Highway Districts in Canyon County. Our Highway District boundaries primarily include the Northeastern area of Canyon County, surrounding Caldwell and Middleton. Highway District No. 4 was formed in 1981 to maintain public rights-of-way, roads, and bridges in the highway system, within the District's boundaries, excluding state highways and public streets within city limits.
The Highway District is a political subdivision of the State of Idaho and, according to state law, functions like a corporation. It is a special-purpose district and is not part of the state, city or county governments.
Total Miles in District:
326.41
Improved Miles:
323.62
Gravel Miles:
2.79
Effective August 22, 2022
HD4 began collecting development impact fees for the Mid-Star Service Area with all access permits issued for new residential, commercial, or industrial development. This includes the unincorporated areas around Middleton and Star lying north of the Boise River, and a small area north of Lincoln Road within one mile from Middleton Road.
See our Transportation Impact Fee webpage for more information.