Eight different players were on the scoresheet as Ben Smith's side rolled over their opponents to move top of Group B after one match.
Karen Bye, the leading US scorer in Nagano, and newcomer Natalie Darwitz both scored a pair of goals.
And the US also looked just as strong defensively, allowing the overmatched Germans a scant eight shots on goal while peppering 57 efforts at their opponents' net.
"We came out a little nervous and I think it showed. But by the second period we relaxed and it really became more of a flowing game for us," said captain Cammi Granato.
The US are favourites for gold with Canada, who top Group A, their most likely opponents in the final.
The two teams battled it out for gold four years ago with the Americans winning 3-1 in Japan.
In other Group B action on Tuesday, Finland caused something of an upset by beating China 4-0.
Karoliina Rantamaki opened the scoring during a power play halfway through the second period.
Katja Riipi, Emma Laaksonen and Saija Siirvio also found the back of the net withTuula Puputti keeping a clean sheet in the Finnish goal.
China had been touted as strong contenders for the bronze medal coming into the tournament.