Now let's contrast the two elections (1948, 1968) involving racists seceding from the mainstream Democratic Party to form a Third Party.
Thurmond 1948, Wallace 1968 -- dark green
Thurmond 1948, Nixon 1968 -- medium green
Truman 1948, Wallace 1968 -- light green
== NO STATE WENT FROM DEWEY TO WALLACE ==
Truman 1948, Humphrey 1968 -- red
did not vote 1948, Humphrey 1968 -- pink
Truman 1948, Nixon 1968 -- white
Dewey 1948, Humphrey 1968 -- yellow
Dewey 1948, Nixon 1968 -- dark blue
did not vote 1948, Nixon 1968 -- light blue
....I'm going to figure that Thomas E. Dewey was not a good campaigner. He must have assumed that Harry Truman was so awful that few could ever vote for such a hack.
Strom Thurmond took votes away from Truman -- but not Dewey. Thurmond had no political strength outside the core South. He did not appear on the ballot, apparently, in many Northern states, but it would have done him no good. He got 0.17% of the vote in North Dakota, which is clearly not a Southern state and never was, and 0.03% of the vote in California. Off the core of the South he got:
Of those states, Truman won all but Maryland. Henry Wallace did better in Maryland than did Dewey. Oddly, Truman lost Maryland by a margin less than the (Henry) Wallace vote of 1948. Wallace ran to the left (some say very far to the left) of Truman.
Thurmond was largely a protest vote. Most of the Thurmond vote would return to the Democratic fold in 1952 and 1956.
George Wallace had bigger ambitions than Thurmond; he actively campaigned outside the South. He got 12.07% of the vote in Alaska, 12.55% of the vote in Idaho, 11.45% in Indiana, 10.19% in Kansas, 10.04% of the vote in Michigan, 13.25% in New Jersey, and 11.81% of the vote in Ohio, suggesting that he was appealing to more than a protest vote on race.
Add the Wallace vote to the Humphrey vote, and Humphrey wins decisively. America really no longer has Richard Nixon to 'kick around'. Using Indiana as an example of the argument that Humphrey would have won like Truman had he also won the Wallace vote, Nixon would have barely won Indiana, much as Dewey did in 1948. Republicans do not win the Presidency when they barely win Indiana, as in 1948. Ruling out states in which Wallace won 10% or more of the vote, Humphrey would have won in addition to the 191 electoral votes that he in fact won:
New Jersey 17
total shift 101
...enough for 282 electoral votes.
So why do I not mention some other states like Ohio? Because I would then need to discuss such states as Florida and Virginia.
All right. The Democratic Party was in disarray in 1968. Robert F. Kennedy might have won the nomination and gotten a result closer to Truman 1948... or my scenario. Humphrey pieced together most of a splintered coalition reeling from the failure of the Vietnam War. Nixon had no problem with Party unity.