The vote could pave the way for the stadium's demolition, though county officials could come up with another proposal to try to save the iconic Houston landmark, which sits next to Reliant Stadium, home of the National Football League's Houston Texans.
"Clearly, on the issue of the dome, the voters have rejected the proposal and the propose bond issue, and so Commissioners Court will have to make a decision as to where we go from here," Harris County judge Ed Emmett told reporters in Houston.
The referendum would have created 350,000 square feet of column-free exhibition space by raising the Astrodome's floor to street level and removing the seats. There would have been green space and a plaza around the structure.
Former Astros president and general manager Tal Smith, who served as the franchise's liaison during the construction of the Astrodome and was involved in many of its innovations, said he was very disappointed by the vote.
"I regret the way the Dome has deteriorated and was neglected in recent years," Smith said. "It doesn't bear any resemblance to the magnificent structure that it was in the 1960s and 1970s. It attracted worldwide attention for the structure itself and Houston and Harris County. It was so distinctive and revolutionized sports venues.
"It was truly magnificent, and I regret there are people in this area that did not have the opportunity to really experience the Astrodome during its glory days. It was truly glorious."
The Astrodome, built for $35 million, was the vision of former Houston mayor Roy Hofheinz, who boldly proclaimed that baseball could be played indoors and away from Houston's oppressive summer heat and menacing mosquitoes.
When Major League Baseball awarded an expansion franchise to Houston to begin play as the Colt .45s in 1962, the team played in a makeshift stadium next to the construction site of the Astrodome. By the time the Astros and Yankees played an exhibition to open the Astrodome on April 9, 1965, it was already billed as the "Eighth Wonder of the World."
"It was Judge Hofheinz's vision, and he was the mastermind," Smith said.
The playing surface was originally natural grass, which grew because of the semi-transparent panes of glass on the Astrodome's roof. When players had trouble seeing fly balls, however, the panes were painted, and the grass died. That led to the invention of AstroTurf, which only further cemented the Dome's legacy.
Along the way, the Astrodome played host to the NFL's Houston Oilers, the Houston Livestock Show and Rodeo and numerous special events. Elvis Presley sang inside the Dome. Muhammad Ali fought inside the Dome. And the University of Houston, led by Elvin Hayes, took down mighty UCLA and Lew Alcindor -- better known as Kareem Abdul-Jabbar -- before 52,000 college basketball fans in 1968 during the "Game of the Century."
"In its early years, it was really breathtaking," Smith said. "By '76 and '77, it showed wear and tear, but in its early years, it was absolutely magnificent. Just glorious. People would walk in and were just in awe. Not just the fans, but the athletes, players and performers themselves. There were so many notable events there.
"It went beyond baseball and football. It was a magnificent structure, and it meant so much to Houston and Harris County. It really attracted worldwide attention."
Those who grew up in Houston know how special the Astrodome is to the community. It's woven into the city's fabric as much as the space program and oil, but now, the landmark's fate is once again up in the air.
"It was not just another ballpark," Smith said. "It was the Astrodome, and what's why it wore the title of the 'Eighth Wonder of the World.' It really was. People say domed stadiums are commonplace, and that might be true, but we might not have any of them had it not been for the Astros and Roy Hofheinz's vision and great work by local architects and engineering firms.
"Great people really decided to create something that was absolutely beautiful."