Why is JR divided into JR East Japan and JR West Japan?

The East Japan Passenger Railway, commonly known as JR East Japan, is one of the seven major Japanese railway companies in Japan. Besides being the largest company in JR Group, it is also the largest passenger railway operator in the world. The East Japan Passenger Railway mainly deals with the passenger transport business of Japan Railway in the capital circle (most areas of Kanto and Jiaxinyue) and the northeast region.

JR-West Japan (JR West and JR W for short) is one of the seven JR railway companies in Japan.

The East-West Japan Passenger Railway was established in April 1987, which is a privatized company separated from the Japanese state-owned railway operated by the government. Because the main railway line is in the west of Japan. So it is called: JR West Japan Railway Company, and JR East Japan Railway Company is responsible for the railway operation in Northeast Japan.

The following is the operation route map of the subsidiary of Japan Railway Corporation, and you will understand why.