American Crossroads, Karl Rove’s Super PAC, has raised $56 million since its inception in 2010. And three Texas business moguls—Harold Simmons, Bob Perry, and Robert Rowling—have collectively given $30.5 million, more than half of that total, the Hill‘s Cameron Joseph reported.

Reclusive Dallas billionaire Simmons, who given away more than $18 million dollars this election cycle, gave a full $14 million of that to American Crossroads, according to Michael Beckel of iWatch News. Simmons’s “contributions include $10 million from his own checkbook and $4 million from corporate accounts that he controls — Contran Corp. ($2 million), Dixie Rice Agricultural Corp. ($1 million) and Southwest Louisiana Land, LLC ($1 million).”

Houston-based homebuilder Bob Perry gave $7 million to American Crossroads in 2010 and has given an additional $2.5 to the group this election cycle. Writing about Perry in 2010, Clare O’Connor of Forbes said the homebuilder “stays below the radar, hitting headlines only for his huge campaign expenditures.” Previous to 2010, “Perry was best known for financing the Swift Boat campaign that halted John Kerry’s presidential run in 2004.”

Robert Rowling, the billionaire founder and CEO of TRT Holdings, clocks in as American Crossroads’s number three donor. Rowling, who is based in Dallas, gave a total of $7 million in personal and corporate contributions, Beckel wrote. (TRT Holdings owns Omni Hotels, Gold’s Gym, and Tana Exploration Co.)

Beckel elaborated on the role these tycoons have historically played as political donors:

Simmons and Perry have long been financiers of conservative causes. Their beneficiaries have included the Swift Boat Veterans group that infamously attacked Democratic presidential candidate Massachusetts Sen. John Kerry in 2004 and helped keep President George W. Bush in the White House.

Rowling, too, has long been among the GOP’s premier moneymen. He was a “bundler” for Bush’s presidential campaigns in both 2000 and 2004, which means he solicited friends and business associates for contributions to Bush and was credited for raising a total greatly exceeding what he could personally give.

Want to know more about who else donated to American Crossroads? Sift through the donations yourself at OpenSecrets.org.