In the 1970s, Covenant Presbytery (PCUS) and Trinity Presbytery (UPCUSA) collaborated on missions due to their shared geographical boundaries, eventually forming a union presbytery. On January 4, 1979, they established Grace Union Presbytery at First Presbyterian Church in Dallas, which was later renamed by dropping “Union” in 1983 after the merger of the PCUS and UPCUSA. 

The Presbyterian Church in the United States of America originated from the first General Assembly in Philadelphia on May 24, 1789. In 1810, many Presbyterians west of the Allegheny Mountains left to form the Cumberland Presbyterian Church, which began its mission in Texas in 1827 along the Red River. Texas Presbytery was organized on November 27, 1837, and in 1843, the Cumberland Presbyterian Synod of Texas was formed with three presbyteries: Texas, Red River, and Colorado.

In Central Texas, mission work by the Presbyterian Church in the USA began in 1833, leading to the formation of the Presbytery of Texas in 1840. The Synod of Texas was organized in 1851, thriving until many churches joined the Presbyterian Church in the Confederate States of America in 1862. After the Civil War, this body became the Presbyterian Church in the United States, which includes the Covenant Presbytery.

The Presbytery of Austin was organized on July 16, 1868, marking the resurgence of the Presbyterian Church in Texas. By 1875, the Synod of Texas included three presbyteries, and a vigorous mission program established numerous churches. In 1906, the Cumberland Presbyterian Church reunited with its mother church, strengthening the presence of Presbyterianism in Texas. In 1958, this denomination merged with the United Presbyterian Church of North America to form the United Presbyterian Church in the United States of America, of which Trinity Presbytery is a member.