Hi,
You will need to get PCC from all those countries where you lived for 6 months or more since turning the age of 18, so yes you need PCC from US does not matter if you are a citizen or not. You got incorrect information many applicants on this forum got there PCC from US. However US PCC takes time, they say about 16 weeks but on average you will get it in 8 weeks so better to apply for that ASAP because this is the only PCC which will take your alot of time. Below is the link of how to get PCC from USA.
http://www.canadavisa.com/canadian-immigration-state-police-clearance.htmlCheers
Saki