My first degree was in world history. I loved every second of that degree but I worked full time and couldn't take advantage of internships which would have at least got my foot in the door at the various museums in my city. After graduating I couldn't find anything. (At the time i lived in atlanta so i was searching there but willing to move wherever.) The jobs I could find paid less than what I made starting out as a teacher. Their job descriptions would say things like "entry level" but would go to individuals with 10+ years of experience and masters degrees. The government always had jobs posted that sounded like a dream but I never heard back from a single one.
I got frustrated and went back to school for history education. I got a job almost immediately.
Shortly thereafter I met a guy who did the same world history program that I did. He got hired straight out of his masters program at the University we went to. He runs the education outreach program at their holocaust museum. So obviously people are finding jobs! However out of the dozens of people I met through the American and world history programs he was the only one to land a job in the field. Several joined the military and most became teachers. (Many don't teach history and had to get certified in other areas... myself included.)
I still hope to complete a masters degree in either straight history or public history and eventually move into museum work. I'm volunteering during my summers off with local history/preservation groups. I've put in volunteer applications with all the nearby museums too. My hope is that one day I can make the career switch without losing too much in the process... either way I enjoy my job and I am still actively involved with history. I love it as much as I always did! I just don't get paid for doing it.
Tl;dr: I got a history degree and had to go back to get an education degree because I couldn't find jobs.
What do you want to do with your degree? Academia? Museum work? Research? Do you want to specialize in something- ie archaeology? Theology? Architecture?
Most work in the field of history involves good research skills and then applying those skills to communicate your findings to others through presentation, writing, or other media. If you want to succeed as an historian, you should really work hard to develop your writing and critical analysis abilities. If you can write well, you can do anything- but it is also highly beneficial to have an idea of what you want to do so you can begin tailoring your education to benefit your ultimate career.
This isn't what you want to do but just FYI I studied an unrelated field and just took history as a minor. It allowed me to do what I love and also learn a more... ehm, financially workable trade. Just throwin that out there.
There are no jobs. There are no jobs. There are no jobs.
I hope you'll be applying to the best colleges in the country, because this will ease your way into one of the top tier History graduate programs in the country. This will be critical to finding employment after grad school.
This, of course, assumes you make it through grad school to the Ph.D.--only about one-third finish.
Are you independently wealthy? If not, you can look forward to mountains of debt piled onto your undergraduate debt. It takes about eight years to get through the graduate program, so that's eight years of zero income while all your peers are earning money right out of college. So when you finally enter the working world at 30, you'll have more debt to pay off and fewer years to save for retirement. After ten years as a tenured professor I was making only $45,000 annually.
The vast majority of history professors, of course, are not tenure-track. They are adjuncts, which means they work without contracts, as nomads, wherever they can find work. No office, no health care, no benefits. Across all fields, adjuncts make about $20,000 to $25,000 per year.
Do not pursue a Ph.D. in History. I don't even recommend getting a B.A. in History. There is nothing out there. There are very few jobs which require you to know Napoleon's birthday. Obama doesn't want you to become a History major, Trump doesn't want you to become a History major. There are too many people pursuing humanities degrees and society does not create enough jobs in these fields. If you love history, get a STEM degree like a normal 21st century person and read history in your spare time.
I can't speak for American history, but I graduated last October with a degree in history and I had no luck whatsoever. And because I tried the education thing and didn't like it, I had to move into a new field. I still love history and annoy my coworkers with history, but my best advice is get a degree that can feed you. History is important, but not important enough apparently to warrant people paying for your services. :'(
As someone trying to complete their dissertation in American history, the field is rough. I won't try and tell you what to do, but I will stress that you should think long and hard about doing this before you try and commit (and you have a few years before you'd have to anyway) here are some bits and pieces that you should incorporate into your decision making:
The American Historical Association recently conducted a study tracking job placement for History PhD recipients 5 years after graduation. Basically, 50% wound up in tenure track faculty jobs at 4 year universities, another 20% were in other faculty positions (usually non-tenure track), and about 24% were scattered into various non-faculty job sectors like K-12 teaching, government, archives/libraries, consulting etc. Note: specialists in American history were 25% LESS likely to get hired. There's a glut of us right now.
So, within 5 years, you'll likely wind up somewhere, but there's an emphasis on faculty professions. But between earning your doctorate and getting settled, you'll likely have to move around the country to wherever the jobs are. Colleagues from my department, for instance, have ended up in Georgia, Alabama, Massachusetts, Utah, Ohio, Michigan, Texas, Washington DC, and more. My school is not in any of those states.
Another note: top tier schools produce enough job applicants to fill the majority of positions. Something like 8% of schools supply the recipients of like 50% of History faculty positions, and I think you can guess some of those 8% schools. During one round of interviews at in my department, all three final applicants came from Princeton. So if you can get into the tippy top graduate programs for your field (example: going to the University of Virginia to study the Civil War), then consider going. If all you can get into is Bumblefuck State University (no offense, BSU students), you might be wasting your time.
An addendum to that: it's possible to re-apply from a masters program. I have colleagues who have "traded-up" to schools like Harvard by using their Masters work to improve their applications.
You mentioned the National Park Service, and a friend happens to work for them. He has an MA, not a PhD, and he has his job because he worked for a time before he even entered grad school. Prior experience and contacts within the organization matter much more than your overt degree in working for the NPS. And my friend? He just recently got a permanent position after years (years) of seasonal positions where there was no guarantee he'd be hired back.
If you go into those faculty positions, your professional duties will likely have 3 pillars: research, teaching, and service. The emphasis placed on each of those three will depend on the school you're hired at. Research is producing new knowledge: writing articles and books, academic conferences, etc. Teaching is what you expect it is: advising students and instructing courses. You'll hear talk of a 2-2 load, 3-3 load, or similar, and this refers to how many courses you teach (2-2 = 2 fall semester courses, 2 in the spring). Service will involve engaging with the university and broader community.
Finally, on money: you will not make much while a grad student. More important than that, though, DO NOT TAKE ON ADDITIONAL DEBT FOR GRAD SCHOOL. If you're a decent candidate for graduate work, and a school is both worth its salt and wants you in their department, you will receive tuition remission and a stipend. I get paid (a little) for my graduate work, and have not paid a cent in tuition since I started. If a program really wants you, they'll pay you.