Yes, the US business letter can be from the US company office which is located out of jurisdiction.(For example - If US business letter is from the San Jose office but traveler lives in Washington DC jurisdiction, it is okay to use the San Jose letterhead).
There is a special template of the US business letter for processing through Indian embassy in Washington DC. The business letter should follow the exact template of the US business letter available on our website to process India visa in Washington DC.
You can access the US business letter template for Washington DC by Clicking Here
You can request your India visa by Clicking Here