The Alamo Regional Mobility Authority (AlamoRMA) was created as the Bexar County Regional Mobility Authority in December 2003 for Bexar County. The initial projects were US-281 from Loop 1604 to Stone Oak Parkway, Loop 1604  from IH-10 to IH-35, US-281 and Loop 1604 interchange; and, IH-10 and Loop 1604 interchange.

Bexar County RMA (AlamoRMA) was the second Regional Mobility Authority authorized by the Texas Transportation Commission. The first RMA authorized was the Central Texas Regional Mobility Authority.

On September 3, 2003, Bexar County filed a petition with the commission for authorization to form an RMA. The petition identifies a potential toll road network as the initial project including new and added capacity improvements on portions of Loop 1604 and US 281, including: Loop 1604 from FM 471 to I-35 North; on US 281 from Loop 1604 to the Comal County line; Northeast I-35 corridor from Loop 1604 to the central business district; and improvement of operations at a couple of interchanges, 1604 and I-10 and 1604 and US 281.

On October 28, 2003, TxDOT conducted a public hearing to receive public comments on the proposed RMA. TxDOT characterized the nature of the vast majority of comments received during the public hearing as being in support of forming the Bexar County RMA. Further TxDOT described most or "probably the majority" of the letters received subsequent to the hearing as having been against forming the RMA. TxDOT also received resolutions in support of forming the RMA from the San Antonio Mobility Coalition, the City of San Antonio, and from the Metropolitian Planning Organization (MPO).

The initial board of directors was composed of seven members, six appointed by the Bexar County Commissioners Court plus the chair appointed by the governor.