is a national highway of Japan connecting Kita-ku, Osaka and Kameoka, Kyoto in the Kansai region of Japan.
National Route 423 has a total length of .
The Minà  Toll Road is a two-lane toll road in Minoh, Osaka that connects the Shin-Meishin Expressway to the southern limits of the city via a tunnel under Mount Minà Â. It is a part of Route 423 that is tolled and maintained by the Osaka Prefectural Road Corporation.
The Shinmidà Â-suji is a controlled-access highway that runs from the northern terminus of the Midà Âsuji in Kita-ku to the southern terminus of the Minà  Toll Road in Minoh. From Kita-ku to Toyonaka, the median of the highway is utilized by the Midà Âsuji Line and Kita-Osaka Kyuko Railway.
Much of what is now National Route 423 was part of the Settan-kaido, a road linking Ikeda in what was Settsu Province and Kameoka in what was then Tanba Province.
In 1964, the portion of the route between Kita-ku and Osaka Prefecture Route 9, known as the Shinmidà Â-suji, was built alongside the extended Midà Âsuji Line to accommodate automobile traffic from Shin-à Âsaka Station into central Osaka. Later in the decade, Shinmidà Â-suji was extended north again along with the Midà Âsuji Line to Suita were the venue for the Expo '70 was. National Route 423 was established in 1982 along the Shinmidà Â-suji, the planned Minà  Toll Road, and the older Settan-kaido.
The Minà  Toll Road section was opened to traffic on 30 May 2007 between Osaka Route 9 and the northern terminus at the IkedaâÂÂMinoh route of National Route 423, completing the route. On 10 December 2017 the highway was connected to the Shin-Meishin Expressway at the northern terminus of the IkedaâÂÂMinoh route and the toll road.
The entire toll road is in Osaka Prefecture.
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