Arizona transportation officials have put out the call for bids to build or upgrade electric vehicle charging stations along interstate highways.

The stations are the first major step in establishing a statewide network of rapid charging stations, with 21 facilities expected to be operating by the end of 2025.

“These stations are intended to reduce range anxiety and encourage use of electric vehicles as a viable alternative to gasoline-powered vehicles,” Arizona Department of Transportation of Safety officials said in a release.

All stations will be privately owned and operated, with federal funds covering 80% of construction costs and the private developer paying 20%, according to the release.

Bids are due April 19, with ADOT awarding contracts this summer. Construction of the privately owned facilities is anticipated to take about a year.

The charging stations are funded through the National Electric Vehicle Infrastructure program which is allocating $5 billion nationwide through the U.S. departments of transportation and energy and $76.5 million for Arizona.

The charging stations generally will be spaced no more than 50 miles apart, ADOT officials said, and must be built beyond the freeway within a mile of an interchange.

Each station must include at least four chargers that can charge a typical electric vehicle within 20-30 minutes.

While the first round of electric vehicle charging stations will focus on interstates, ADOT plans to expand onto other highways starting with an additional round of bids in 2025.

“The plans will evolve based on developments within the electric vehicle industry and by studying the usage patterns of the first set of stations that come online,” officials said in the release.