Numbering
For most of the 20th century apparatus numbering was fairly simple, it simply numbered the apparatus. Engine 2 was the departments second engine, it might be in station 1 with Engine 1 or alone in station 2. Sometimes the descriptive identifier was abbreviated E-1 or ENG-1 instead of Engine 1. This style of identification is still popular but there are now many more methods.
Some departments wanted to give the location as well so they gave the apparatus a number along with the station number, so Engine 12 would be the first engine at station 2 or the second engine at station 1. Departments with large geographic areas also sometimes used this style of numbering but divided it into districts instead of stations. Along the same lines some departments gave the district and the station, so Engine 522 could be district 5, station 2, engine 2. There are many variations but most follow this basic idea.
In the late 1970's many fire departments were having budget problems, as a result it became more cost effective to start sharing resources. Instead of having a neighboring cities firefighters sitting idle while your city burned it became common to write up agreements allowing fire departments to assist each other, this is called mutual aid. This worked so well that people began to wonder why they had to wait for a fire engine from across town when there was one just down the street that belonged to another city, mutual aid was modified to allow the closest unit to respond regardless of jurisdictional boundaries, this is known as automatic aid and it allowed departments to rethink the placement of fire stations for better cost effectiveness. With all of this mixing of fire department vehicles it got confusing, was that Oakland's Engine 1 or Berkeley's Engine 1? As a result many areas changed to a regional numbering system. Most of these systems are three or four digits, usually the first two give the department, the next gives the unit much as the old single digit numbers did. Three digit identifiers are usually used with a descriptive identifier giving the type of apparatus, for example Engine 231 is the 1st engine from the 23rd department in the county. Four digit identifiers usually stand alone, in this the first 2 numbers still stand for the department but the 3rd number identifies the type of apparatus and the 4th gives the station, most provide multiple numbers for engines to allow for more than 9 stations. For example 6811 would be the first engine out of station 1 for the 68th department in the county, 6812 would be the first engine in the departments station 2 and 6821 would be the second engine out of station 1 or the first engine out of station 11. Although the four digit identifiers give the unit type old habits die hard and it is common to see the unit type spelled out as Engine 6811. There are far to many combinations to give them all but hopefully this provides a starting point, besides there is no reason you can not come up with your own method as long as it looks good to you.
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