The Germans ended up winning it all, though they ran out of goals in their next game against England, settling for a 0-0 tie.
She had an effort disallowed for offside inside five minutes but quickly made up for that by nodding in a Kelley O'Hara cross, before Thai goalkeeper Sukanya Chor Charoenying - standing at just 1.65m tall - allowed Lavelle's shot to beat her at the near post.
Lloyd also tied Birgit Prinz's record for longest goal-scoring streak in the Women's World Cup.
If you tuned into the Men's World Cup in 2018, or 2014, or 2010, or 2006, but aren't turned into this year's Women's World Cup, it's time to reconsider.More news: Mozilla Firefox To Have A Paid Subscription Service In October
Morgan got three more to equal the record of Akers set in that game against Taiwan in 1991, while Rapinoe, Pugh and Lloyd joined in too as spectators struggled to keep up with the scoring.
Based on Tuesday's performance, the Americans are likely to blow past their competition in the group stage with matches against Chile and Sweden still to come.
As the match went on, it became clear that Thailand couldn't get close to goal and it failed to break past the Americans' defenders. "But we also feel like we've got more to do. It will be an incredibly hard World Cup", she said.
Morgan opened the goal spree for the title favorites, who are in pursuit of a fourth world crown, with a header in the 12th minute and from then on there was no stopping the champions.More news: Botswana decriminalizes gay sex in landmark Africa case
Samantha Mewis opened the floodgates five minutes after the break as the USA made life miserable for the Thais by regularly finding the back of the net.
Morgan and Mewis knocked home the next two, and Lavelle finished the barrage with her second goal in her debut off an assist from Mewis. Morgan put her arm around Thailand's Miranda Nild, who was wiping away tears on the pitch. "We don't have any excuse and accept they are better", said Thailand coach Nuengrutai Srathongvian. On Tuesday night, in front of a pro-American crowd of 18,591, the USA won 13-0 against Thailand. "Yes, they are all athletes and they will be resilient".
Before the USWNT takes on Chile on Sunday, let's take a look at some of the most lopsided games in World Cup history, including a jaw-dropping qualifier bonus.More news: SA captain du Plessis