1

The most common for your age is the J visa, or the exchange visitor visa.
There are also H visas, temporary worker visas, but these are much more difficult to obtain, and have annual quotas.
Since you are Irish, you could also try the work pilot program.

How to apply for a visa.

Note, all of these need sponsors. They also require to maintain a job to maintain your visa status. In other words, don't expect to work for a couple days or weeks then move on at your leisure. If you leave a job, your visa is void unless you can get a new job/sponsor.

None of this is easy.

2

The most common exchange visitor visas are those for summer work: Camp Counselor and summer work/travel. Unless you have experience as a teacher or youth worker, you must be a current university student to apply for camp counselor. You must be a university student to apply for summer work//travel.

You must go through a designated sponsor, which will charge you a fee. The sponsor is responsible for finding yo a job, although some work/travel sponsors will let you fond your own job. As noted, you are tied to the job, but will have 30 days after it ends to do some travel.

For the Irish pilot program, you also must have registration at a third level certificate- or degree-granting institution or be a recent graduate. This information is from one sponsor of the program, but it gives more details than the embassy web site. Some of the financial information applies only to that sponsor.

3

Lots of kids working the bars here in Chicago on a J visa, but you need to 21 I think.

4

Apply to the nearest "USIT" to you
see.....USIT.IE / VISAS & WORK ABROAD

5

Reach out to Camp American or Bunac, both of whom arrange summer work in the US. They also help with getting a visa.