is it the right address

[Lona.C. 16]

I send my application on Ap/14 by certified usps mail to 

USCIS
P.O. Box 660060
Dallas, TX 75266

the tracking still says on its way to destination , I like to confirm that I send it right with certified USPS and to the right place ? 

[Lona.C. 16]

does anyone know ? I just like to make sure I send it to the right place and they accept certified mail 

[Lona.C. 16]

I live in MA but its the same address as CT to mail it too , 

I send it certified with signature request , I asked the postal worker whats the best way to mail it  and he said

"certified they have to sign for it even if its a PO box,  it will arrive on Monday april 17"

but as of now  tracking still sais in transit to destination