Though Tomorrowland was just completely redone, it still recieved new rides.
America Sings was added in 1974 to pay tribute to the opcoming American Biccentenial. America sings replaced Carousel of Progress in the rotating building. It was another Audio-Animatronic show which showcased songs from various points in American History. It was a big hit, and lasted years after the Biccentenial celebration ended.
America Signs was closed in 1988 not because it lost popularity, but because another attraction went over budget and they needed the Audio-Animatronics for other another attraction. They are currently found in another classic Disney attraction...
Mission to Mars also replaced Flight to the Moon in Tomorrowland in 1973.
In 1974, construction on Space Mountain also started. Although it was built in Magic Kingdom first, the attraction actually dates back to 1967. The idea for Space Mountain came around when Walt Disney wanted a roller coaster type thrill ride to energize an ever aging Tomorrowland, originally called Space Port. Space Mountain took 2 years to build an opened to a huge crowd on May 27, 1977, along with a new restaurant, theater, and Starcade.
Space Mountain became one of the most popular rides in Disneyland, and in 1995 a soundtrack was added to enhance the ride. Much father down the road, Space Mountain would go through a heavy refurbishment and a fe changeovers. But that comes later down the line...
Tomorrowland has always been a land of unrest. So it's no surprise that more changes were instore for Tomorrowland.