Playing Pro in the U.S

Playing professional or semi-professional football is a lifetime career only for a top few. Even if a club signs you, it doesn't mean that you are set for life. It can, however, provide you with additional opportunities and contacts which could help you stay involved in the game as a coach, manager and so on. But always remember that playing football is a short-term job for 99% of all professionals.
Professional teams in the USA
In the United States, there are three professional soccer divisions. The MLS is on top. It is comprised of college draftees from around the US, South and Central Americans brought over with cheap contracts, and aging former stars trying to earn extra bucks. Most youngsters in the MLS get about $30-50,000 per year ($24,000 is the minimum.) The top guns in MLS get twice that sum in a single month. That is still a fraction of what a player gets in a good European league. The best way to get into the MLS is by making yourself noticed at the collegiate level or in lower division like the USL or PDL. Otherwise, it's very difficult to get tryouts with a team form the MLS, unless you have an impressive resume. MLS teams rarely hold open tryouts. Even if they do, it is usually very hard to get noticed, because of the large quantities of applicants. The NY MetroStars had nearly 1000 players show up in February of 2003. Out of them, they selected only two and both of them were sent to the team's reserve squad.
Web Site: MLS Official Web Site
The USL 1 (formerly A-League) is considered one level below the MLS. Teams from both Canada and the US participate in it. They are separated into two conferences (Eastern and Western) with about six teams in each. The USL is played from late spring to early fall so that college players can participate without abandoning their study. The USL league is a major source of players for the MLS. It is a gathering place for promising youngsters and for retiring MLS stars. This league pays around $1000-3000 per month for six months of the year. Many USL teams hold open tryouts. Notice that they are usually held at the end or beginning of the year. Call your local team or search the net to find out about upcoming tryouts.
Web Site: USL Official Web Site
Web Site: Open Tryouts for the A-League (old)
The USL 2 league (formerly PSL or D3 Pro) is one level below the USL 1. It consts of nine teams, separated into two conferences.
The PDL League is for players 23 or younger. It is an amateur league for "professional development." Teams from the higher divisions, or the MLS regularly draft players from the PDL. The PDL League accepts players for tryouts with little restrictions. If you have ability, they will pretty much be interested in you.
Web Site: PDL Official Site
The USL 1, USL 2 and the PDL are united in a single organization called USL (United Soccer Leagues.) College divisions are the other major source of manpower for the MLS and the professional USL leagues. College players are the ideal target for pro teams, because they can be signed for free and have a lot of years ahead of them. The MLS SuperDraft is the system of brining up players from college and the USL leagues into the MLS.