It is not easy, but it is by no means impossible, for UK-trained historians to be appointed to posts in the United States. If you think that you might be interested in applying there, try to plan ahead. Spend some time at a US university during your PhD. US resources are so vast that nearly all PhD topics, whatever your area of history, could benefit from research at one of their institutions. If your own university offers an exchange that gives you a relatively easy route, but if not, remember that many US libraries/research centres offer funding for visiting fellowships, many of which are open to graduate students. You could also apply for a US postdoc. Make sure you attend the AHA at least once, say in the third or fourth year of your PhD. For advice on funding, see Grant Applications section.
The job cycle starts earlier in than in the UK (as does the academic year): start looking in August for the subsequent year. Job postings can be found at H-Net Job Guide, the Chronicle of Higher Education and the AHA listings (for which you have to be a member). The Chronicle also gives good information about navigating the job market. The importance of doing your research about the institution to which you are applying cannot be emphasised too much here. There is a wide range of US universities and liberal arts colleges, both state-funded and private, and you will need to understand the priorities and remit of anywhere you hope to work. The following are useful resources: The Academic Job Search Handbook or the AHA’s relevant publications.
Recruitment procedures in the United States take longer than in the UK. The US market is large, both in terms of posts and applicants, so each year a cohort of new PhDs will be competing for the available jobs in any particular field. For a US graduate student, missing out in the first year after PhD leaves you permanently disadvantaged in subsequent years, because although you may be more experienced, it will also be obvious that you were not successful the first time round. An initial selection is often made at the big conferences, such as the AHA, which many people attend mainly to go to a series of quick-fire interviews in hotel rooms. This is a pretty gruelling process, not for the faint-hearted.
If you get over that first hurdle, you will be invited to the university itself for a couple of days. A typical schedule would be: dinner the first evening, a full day of interviews, job talk and meals, followed by breakfast before departure the next day. During this time you will meet most of your potential colleagues and some students. All of these meetings can influence your chances because it is likely that the whole department (as distinct from a recruitment committee, as in the UK) will vote on the candidates. There is really no time when you are not being interviewed. This process has the advantage of giving you, as well as your potential employers, a good chance to find out if you are suited to the post.
It may then be some weeks, or even months, before you hear the outcome, because other candidates will be doing the same, in sequence rather than all on the same day(s) as in the UK. If you are offered the post, remember that there are no national salary scales and each new recruit engages in a negotiation about salary and other terms and conditions. It is not easy for someone with little experience of US universities to know how to negotiate, but you should bear in mind that it would look odd not to do so. Being modest or unassuming does not have the appeal there that it still tends to have in the UK – instead, it is usually interpreted as undervaluing yourself. Try to get advice about how to negotiate a salary deal from someone who has worked in a US university.
Application materials: Much of the general advice given above is equally valid to US applications. Keep your application letter (cover letter) to 2 pages, although US curricula vitae (or resumés) tend to be longer than in the UK, 10-15 pages. This is partly because US graduate students have more separate components to their doctoral training, although the UK has moved some way in this direction. You should go into detail about your MA, specifying the modules you took, because this covers some of what is done in the early stages of a US doctorate, and also about the skills training you did during your PhD. If your PhD was funded, draw attention to that in your letter and explain, preferably with statistics to back you up, how competitive these awards are. Highlight your teaching experience: there tends to be a perception that UK PhD students graduate with less teaching experience than US students, perhaps because of the shorter time to degree. And more references are required: US applicants compile a dossier of recommendation letters, usually at least 5-6, sometimes more; again this is easier for them to do because they will have been supervised by a committee of five or more people. In drafting your materials, bear in mind that the members of the search committee will not necessarily know what a UK PhD entails (and may well be sceptical as to its comparability with US training), so you will need to explain carefully how it has equipped you for the post, along with your other experience.