Thanks to Mischa for drawing my attention to the following. From the New York Times archives:
U.S. Encouraged by Vietnam Vote:
Officials Cite 83% Turnout Despite Vietcong Terror
by Peter Grose, Special to the New York Times — Sept. 4, 1967
WASHINGTON, Sept. 3– United States officials were surprised and heartened today at the size of turnout in South Vietnam’s presidential election despite a Vietcong terrorist campaign to disrupt the voting.
According to reports from Saigon, 83 per cent of the 5.85 million registered voters cast their ballots yesterday. Many of them risked reprisals threatened by the Vietcong.
The size of the popular vote and the inability of the Vietcong to destroy the election machinery were the two salient facts in a preliminary assessment of the nation election based on the incomplete returns reaching here.
A successful election has long been seen as the keystone in President Johnson’s policy of encouraging the growth of constitutional processes in South Vietnam.
The purpose of the voting was to give legitimacy to the Saigon Government.