My Grandmother is a US Citizen, but my Father isn't.........

Can I apply for Citizenship to the US, or does my father have to become one before me?

Unless you have been naturalized, you don't "apply" for US citizenship. You are or you are not. Your father is or he is not.

If he is not a US citizen, he needs to get sponsored to live in US and then apply for natuarrlization, 3 to 5 years later. In the meantime he mnay or may not be able to sponsor you, in which case you too could move to US and get to aplly for US citizenship in perhaps 10 to 15 years.

So, you need to first determine if your father is or is not a US citizen. If he is, you may be also, If he is not, you will not become one without first getting Green card, which will take years, and then wait 3 more years.

Just a nelsona responded, if he's not a US citizen you are looking at a bazillion years before you can apply. If his mother is a US citizen she could sponsor him. It would take awhile. Then he could sponsor you many years later.

short answer is no, you are not eligible for US citizenship just because your Grandmother is American.

Where and when was your father born? Depending on the laws at the time, he may or may not be eligible for US citizenship. However, even if he is eligible, you probably wouldn't be, because your father would have to have lived in the US for some number of years before you were born, in order to register your birth abroad as a US citizen.

Unfortately, the US does not have an Anscestry visa like the UK does, so we are not eligible for immigration to the US based on our grandparents citizenship.