Unlike a typical UK official letter format, the US has a couple of variations, the full block format and modified block format. The former simply means all elements of the letter, from the return address at the top down to the writer's name at the foot, are justified left. the latter, on the other hand, incorporates some elements to the right or centre, rather like the UK official letter format.
Here's a surprise. You're not a real person. Not to a recruiter. At this point you're just facts and data on a dull piece of paper. But it's okay, so are other candidates. The good news is that they are all using examples of good cover letters from the web. Your first opportunity to come alive is how you go beyond your resume cover letter format to make your letter better. With these tips, your letter can breathe life into you, make you memorable to the employer.