Simplify the following text for a Grade 4 native English-speaking person.
Original: North Yorkshire was formed on 1 April 1974 as a result of the Local Government Act 1972 , and covers most of the lands of the historic North Riding , as well as the northern half of the West Riding , the northern and eastern fringes of the East Riding of Yorkshire and the former county borough of York .
Simplified: The three parts of Yorkshire used to be called the West Riding , the East Riding , and the North Riding . in 1974 , the boundaries and names changed .