We now know that more than 75,000 people attended the show, which is about 20,000 more people than RodeoHouston has been averaging over the last few years on opening night.
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Viewers sent us pictures and videos of the long lines with some people saying they had to wait for nearly an hour to get in.
WATCH: Long lines stretch outside NRG Stadium
Long lines outside Garth Brooks concert at RodeoHouston
Video shot by ABC13 shows workers trying to scan cell phones that have electronic tickets on them.
While ticket holders said there were issues with electronic readers, thought to be related to the rollout of Flash Seats at the rodeo, ticket takers said an influx of people coming from NRG Park slowed down the process.
Ticket takers said lines swelled at the BHP Billiton entrance as many tried to enter from the carnival grounds and livestock show.
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There were so many people standing in line waiting to get their tickets scanned, that rodeo officials sent over extra scanners.
Eventually, the workers were told to stop scanning and to visually inspect tickets and smartphones before allowing people through the turnstiles.
Rodeo officials say part of the problem is that people started lining up very early to get into the stadium.
Hundreds caught in long lines outside NRG Stadium
RodeoHouston issued this statement Tuesday night as Garth Brooks was about to take the stage:
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Due to the excitement of opening day at the Houston Livestock Show and Rodeo and Garth Brooks in concert, we experienced visitors lining up at the gates earlier than normal, which caused congestion at some gates. To ensure guests could enter the gates and enjoy the rodeo and concert, we visually scanned their ticket or mobile app, instead of digitally scanning, in order to alleviate the congestion. We have now resumed normal scanning procedures.
Rodeo officials say they plan to meet Wednesday morning to determine what they should do moving forward.
Little Big Town will take the stage Wednesday night.
PHOTOS: Country legend Garth Brooks returns to RodeoHouston
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