[1] In 1927, Clark married Anne Metcalfe of Greenville, Mississippi, the heir to the largest cotton plantation system in the South.

He remained active in the Democratic Party and was associated with those opposed to the liberal elements, led by Texas Senator Ralph Yarborough.

In 1974, President Nixon appointed Clark to the General Advisory Committee of the United States Arms Control and Disarmament Agency.

[1] In 2003, Barr McClellan, an attorney who had been employed by Clark's law firm in Austin, published Blood, Money & Power: How LBJ Killed JFK.

[5] Former US presidents Gerald Ford and Jimmy Carter protested, and former Johnson staffers Bill Moyers and Jack Valenti asked The History Channel to investigate the charges.

On April 2, 2004, after having three historians examine the charges, The History Channel issued a press release stating that the claim of Johnson's complicity "is entirely unfounded and does not hold up to scrutiny.... [The show] fell short of the high standards that the network sets for itself.

The History Channel apologizes to its viewers and to Mrs. Lady Bird Johnson and her family for airing the show.