why did Humphrey do so (relatively) well in Texas in 1968?

[Indy Texas]

Texas never jumped on the Lost Cause bandwagon with the Deep South. The state Democratic Party backed Truman over Thurmond in '48 and Humphrey over Wallace in '68. I attribute that to the following:

1) Texans were a major part of the national Democratic establishment for most of the 20th century. You had powerbrokers in elected office (John Nance Garner, Sam Rayburn, LBJ, Wright Patman) and behind the scenes (Jesse H. Jones, Robert Strauss). It would have been counterintuitive for Texas to buck the national party when the national party was so good to them.

2) Integration was not the inflammatory issue in Texas that it was in the Deep South and in Northern inner cities. There basically weren't/aren't any blacks west of the Brazos River, so it was a non-issue for half the state. Houston's business establishment and the black community had a gentlemen's agreement that desegregation would be phased in gradually (i.e. movie theaters one month, swimming pools the next). That basically leaves Dallas (which by that time had declared allegiance to Goldwater-style Sunbelt conservatism rather than Dixiecrat revanchism) and rural East Texas (which, coincidentally, is the only part of the state where Wallace got any votes). As a result, the conservative Democrats either stuck with Humphrey or voted for Nixon.

[Indy Texas]

That'd make sense except that LBJ was privately for Rockefeller in '68.