In a statement, Spain's transport ministry said the 5.5-billion-euro ($5.9 billion) agreement would see Renfe work alongside its US partner to develop and operate a line between Houston and Dallas that is to become operational in 2026.
The two firms have signed a preliminary agreement but it is still in draft phase, said Renfe, Spain's national rail operator.
The Italian construction and engineering firm Salini Impregilo will be in charge of building the 386-kilometre (240-mile) line, the statement said.
For Renfe, the contract's design and construction phase is worth about $311 million, while operating and maintaining the line from 2026 to 2042 is expected to bring in another $5.6 billion.
Described by Texas Central as the “bullet train”, the project aims to link the two cities in less than 90 minutes including a stop at Brazos Valley.
Texas Central Partners is a private company set up for the rail project, which Renfe has described as the first-ever high-speed line in the United States.
The US company Amtrak runs Acela trains between Boston and Washington however that it says can hit speeds of up to 150 miles per hour.