The obvious answer is because the numbers then can be associated with a particular geographic area.
Except that the particular geographic area can be HUGE!
4 land extends from just below the Mason Dixon Line to the Florida Keys and from the Atlantic to the Mississippi. 5 land from the state of Mississippi to New Mexico and from the Gulf to Arkansas. 0 land from the Mississippi to the Rockies. 7 land is HUGE - from Canada and the Pacific Northwest to Mexico!
In other words, having the call match the district didn't really tell you all that much except in a few special cases. For many hams, the much bigger issue was having to change calls every time they moved across a call district boundary. The rules changed 35+ years ago, because we hams wanted them to.
To take the problem that not being the case causes: imagine if all callsign prefixes were available to all countries. N2 might be New York or New Jersey -- or it might be Taiwan or Madagascar.
Not the same thing at all, because different countries are administered by different governments.
I would love to go back to when if you were outside your call district you had to identify as such, for example N2EY/3...
Except that was never the case.
The way it actually worked was this:
Until the mid-1970s (not sure of the exact date) you had to submit a station location to FCC to get a station license. It had to be an actual location; a PO box wasn't enough. The call FCC issued would match the station location.
Whenever you operated away from the station location on the license, you had to use the slant bar or the "mobile" or "portable" voice designator. This was true regardless of district or distance. I was "mobile three" or whatever until I pulled into the driveway.
Then FCC decided that the call didn't have to match the district. They also decided that you didn't have to indicate portable or mobile either. Not sure which went away first or if they went away together. I seem to recall that this was done in part because FCC's DF capabilities rendered it moot.
I had a 3 land call for ten years, from 1967 to 1977. Then I moved to New York state and got this 2 land 1x2, sequentially issued.
After a few years in 2 land, I moved back to 3 land. At the time, I could have gotten a 3 land 1x2, but if I did, FCC would not have reissued this call. So I kept it, because it meant some other ham could have a 1x2.
Now it is 34 years since I moved back to 3 land. I think I'll keep it.
73 de Jim, N2EY
