VOR stations began development in the United States in the year of 1937. By 1946, they were ready to be deployed across the nation.
In 2000 there were approximately 1,033 VOR stations situated in the United States. They are gradually being phased out and replaced by GPS. By 2013, there were only 967 stations remaining in the US.
The FAA has a program that is working to decommission around 34% of the VOR stations across the United States. This is equivalent to 307 VOR stations, of which 82 have already been discontinued. By 2030 the program is set to be completed and there will be 589 VOR stations remaining across the country.
This is following a program called the MON (minimum operational network). This program aims to enhance the service volumes of the remaining ground stations to ensure the country is still covered. This system is designed to be a backup if the GPS fails or is disrupted for some reason.