WASHINGTON — For all the fears of foreign sabotage and security lapses in voting machines, the biggest nightmares to confront election officials during the year’s biggest primary balloting on Tuesday mostly proved more mundane: unexpected numbers of voters, at polling places that were unprepared to handle them.

On a day when most voting went smoothly, the two largest states in the Super Tuesday elections, California and Texas, struggled with hourslong lines in some major cities and complaints from some voting-rights groups that officials were seeking to reduce turnout for political reasons.

The problems were particularly severe in Texas, a state with some of the nation’s strictest voting requirements and lowest voter turnout. In the most notorious breakdown, some voters at Texas Southern University, a historically black institution in Houston, waited as long as seven hours to cast a ballot.

Some critics complained on Twitter and elsewhere that the delays amounted to voter suppression in a state where Republicans have been frequently sued, sometimes successfully, for trying to minimize Democratic power. But Texas elections are tightly controlled by local officials, not state ones. And in big cities like Houston and Austin which had the biggest problems on Tuesday, those officials are Democrats with scant reason to depress turnout in Democratic urban strongholds.