Rae kicked a conversion and two penalties in England's win
England 18 (0):
Tries: Oliver, Clark
Pens: Rae 2
USA 0 (0)
England got off to a solid start in the Women's Rugby World Cup by overcoming a physical USA side in Edmonton, Canada.
Replacement fly-half Shelley Rae, who came on for the injured Karen Andrew after just 17 minutes, opened the scoring with a 50th-minute penalty.
She then converted Kim Oliver's try before slotting a second penalty, and prop Rochelle Clark's late score, after Kim Shaylor's fine run, sealed victory.
"We are glad to have got a win under our belts," said coach Geoff Richards.
"There is room for improvement before we play South Africa on Monday, but we always knew this was going to be a difficult game.
"The US are a tough side who are very fit and strong with pace."
Scotland brushed aside Spain 24-0, but Ireland were thrashed 43-0 by France.
Top seeds New Zealand began their bid for a third straight crown by thumping hosts Canada 66-7.
World Cup results:
England 18-0 USA
Ireland 0-43 France
Spain 0-24 Scotland
Australia 68-12 South Africa
Kazakhstan 5-20 Samoa
New Zealand 66-7 Canada
Charlotte Barras (Lichfield); Nicola Crawford (Worcester), Sue Day (Wasps), Kim Oliver (Clifton), Kim Shaylor (Worcester); Karen Andrew (Saracens), Jo Yapp (capt, Worcester); Rochelle Clark (Henley), Amy Garnett (Saracens), Vanessa Gray (Wasps), Jennifer Sutton (Richmond), Tamara Taylor (Thirsk), Georgia Stevens (Clifton), Margaret Alphonsi (Saracens), Catherine Spencer (Folkestone).
Replacements: Selena Rudge (Wasps), Katy Storie (Clifton), Jenny Lyne (Richmond), Helen Clayton (Saracens), Amy Turner (Wasps), Shelley Rae (Wasps), Michaela Staniford (Henley).