Observerships/ externship opportunities:

So foremost an observership/ externship can serve two purposes-firstly, LOR. A uni program mostly offers observership instead of an externship and doing it from a university program is generally better because the name of the program brings added benefit. This will get you an LOR and an experience which stands out on your CV. Secondly, doing a rotation at a community program and making a good impression may guarantee you a call from there for an interview alongside a LOR. Lastly, a private clinic rotation should be considered only if the above options are not somehow an option for you because if the person you are rotating with is not on the faculty at some place, the LOR strength is generally on the low side.

So generally both observership and externship are considered USCE-US Clinical Experience-observership means following a physician, observing physician-patient encounters, presentations. You can make the most of the experience by volunteering to do more, asking for any research opportunities while on the rotation. Usually this involves no hands-on experience but may vary as per your attending’s discretion. Externship is hands-on clinical experience where you are allowed to take history, do a physical exam, type in patient notes.

While sending an email, a peronsalized email mentioning about what in particular inspired you to reach out to him/ her- their areas of research interest vs. shared interest in the field of application usually yields better results. As for the attachments for the email, attach your CV and USMLE score report and please do re-check your grammar and sentence structure.
PS: persistence is the key here too... 🙂
And research/USCE is all icing on the cake and by no means an alternative to Usmle scores which are the primary in the residency pursuit process.

Below is a list by no means all encompassing but some places that I am aware of, please feel free to add to the list:

-Rush chicago-email coordinator abhi but you can apply when in US
-MD anderson houston-search google for pakistan faculty-you can also contact other faculty. send personalized emails.
-Albert einstein philly- 2 wks will cost 800$ but will make your prospects of an interview brighter at this program-do not give LOR though-PhysicianObserver@einstein.edu
-florida hospital-email faculty or get in touch with seniors there-Firstname.lastname.md@flhosp.org
-univ of miami- $1600/month-ocata@miami.edu-ask her for application packet
-Cleveland clinic-both florida and cleveland-big name-definitely worth a try
-baylor houston-email faculty-he takes lots of ppl, try alternative-mehboob.alam@bcm.edu
-oklohama uni-ask faculty and seniors if offering observerships
-oschner medical centre- email faculty
-LSU-Louisiana State University email faculty
-Uni of wisconsin-email faculty
-Indiana uni-email faculty
-Houston methodist-contact faculty
-SUNY upstate
-Cook county-chicago-community hospital in chicago
-Providence hospital washington DC
--Heart and vascular institute detroit-fill online form
-rochester general hospital-email coordintor/ faculty
-Mt Sinai New York-email
-Uni of Illinios Chicago
-Mt Sinai florida
-Allegheny

Research opportunities: mostly require J visa-mostly require 1yr commitment and are done after graduation:
-mayo clinic
-Harvard
-Rush chicago
-uni of Pittsburgh
-Stanford
-uni of miami
-uni of arizona
-uni of alabama

Hopes this helps someone...