Monday, October 30, 2017

The History of Chicago / Evanston Telephone Exchanges Including Their Two-Letter Codes and Meanings.

Contrary to popular belief, there were no central office prefixes in the beginning. To place a call on June 26, 1878, when the Bell-licensed Chicago Telephonic Exchange first opened, the subscriber merely told the operator the name and address of the party desired.
1880s Telephone Switchboard Operator. 
For purposes of identification, the original telephone switchboard at 125 LaSalle St. was known as Central office. Two other offices soon opened and were called the Halsted Street branch and the Canal Street branch.
By 1883, these three central offices had grown to 11, and around that time the Bell System-affiliated Chicago Telephone Company (formed in 1881) began to refer to most of them by number. Thus, the switchboard at 125 LaSalle St. became known as the № 2 office. By then, too, subscribers were requested to call by number rather than by name.
Chicago telephone switchboard in the 1880s. (photo via Illinois Bell)
The initial digit of the phone number generally indicated the telephone central office; that is, the subscriber who had “3123” as the call number was served from № 3 office at Chicago Ave. and Clark St. The three offices lying just outside the city limits had no numerical designation and were known as Stock Yards, Oakland and Ravenswood. In 1889, Stock Yards was changed to Yards and Ravenswood to Lake View. In that same year, telephone growth brought about the first use of 5-digit numbers, the Oakland series running from 9800 to 10,999 and the Lake View series from 12,001 to 12,499. This first call number system was inflexible, however, because it allowed little latitude for growth.

By 1892, on the eve of the opening of the World’s Columbian Exposition, it became apparent that the city was rapidly outgrowing the old numbering scheme, and in that year the change to a system of combined prefix and number was made. Beginning February 15, a subscriber served from № 3 office had his/her number change from “3123” to “North 123.”  The entire list of changes:

Old Designation                   Serving #s                          Changed to
 2 office                             1 to 2999                             Main 1 to Main 2999
 3                                        3001 to 3999                       North 1 to North 999
 4 & 5                                 4000 to 5399                        Main 4000 to Main 5399
 7                                        7001 to 7999                       West 1 to West 999
 8                                        8001 to 8999                       South 1 to South 999
 9                                        9001 to 9499                       Canal 1 to Canal 499
Yards                                     9500 to 9799                       Yards 500 to Yards 799
Oakland                                 9800 to 10,999                    Oakland 800 to Oakland 999
Lake View                             12,001 to 12,499                  Lake View 1 to Lake View 499

Telephone numbers, therefore, started using the central office name as the prefix. This second system remained in effect for nearly 30 years.

In June 1921, Illinois Bell Telephone Company (formed in December 1920 from the merger of Chicago Telephone Company and the Illinois properties of Central Union Telephone Company) adopted the citywide 3-letter 4-number plan, effective with the delivery of the October telephone directory. At that time, all phone numbers with less than four digits were changed to add zeros ahead of the number to make four numerals in all cases (for example, “NORth 0029”).  Certain names, such as “Monticello,” were replaced because their numerical equivalents, in this case “666,” conflicted with other existing offices, like “Monroe.” As a result, “Monticello” became “Juniper.” This change was necessary for the launch of automatic dial service, first introduced in Chicago with the cutover of “CENtral” prefix (in the Franklin Building at 315 W. Washington St.) on June 9, 1923.

The fourth alteration in Chicago’s calling plan was the conversion to 2-letters and 5-numbers across the city on September 18, 1948 (for instance, “CEntral 6-1234”). As with the implementation of central office prefixes in 1892, the change to the 2-letter 5-number plan was necessary to provide additional telephone numbers required by the enormous demand for phone service after World War II.


The following is the complete list of Chicago and Evanston central office names and their corresponding prefixes, adopted in 1948. This system allowed for additional prefix equivalents without the invention of new exchange names.

ABerdeen........... AB 4
ALbany............. AL 2
AMbassador......... AM 2
ANdover............ AN 3
ARdmore............ AR 1
ARmitage........... AR 6
ATlantic........... AT 5
AUstin............. AU 7
AVenue............. AV 2,3&6

BAyport............ BA 1
BElmont............ BE 5
BErkshire.......... BE 7
BEverly............ BE 3&8
BIshop............. BI 2&7
BIttersweet........ BI 8
BOulevard.......... BO 8
BRiargate.......... BR 4
BRoadway........... BR 3,4&5
BRunswick.......... BR 8
BUckingham......... BU 1
BUtterfield........ BU 8

CAlumet............ CA 5
CAnal.............. CA 6
CApitol............ CA 7
CAthedraL.......... CA 8
CEdarcrest......... CE 3
CEntral............ CE 6
CHesapeake......... CH 3
CLiffside.......... CL 4
COlumbus........... CO 1
COmmodore.......... CO 4
COrnelia........... CO 7
CRawford........... CR 7

DAnube............. DA 6
DAvis.............. DA 8
DEarborn........... DE 2
DElaware........... DE 7
DIckens............ DI 2
DIversey........... DI 8
DOrchester......... DO 3
DRexel............. DR 3

EAstgate........... EA 7
EDgewater.......... ED 4
ELmdrive........... EL 6
ENglewood.......... EN 4
ESsex.............. ES 5
EStebrook.......... ES 8&9
EVerglade.......... EV 4

FAirfax............ FA 4
FInancial.......... FI 6
FIre............... FI 7
FRanklin........... FR 2
FRontier........... FR 4&6
FUlton............. FU 5

GArden............. GA 4
GLadstone.......... GL 5
GRaceland.......... GR 2&7
GReenleaf.......... GR 5
GRovehill.......... GR 6

HArrison........... HA 7
HAymarket.......... HA 1
HEmlock............ HE 4&6
HIlltop............ HI 5
HOllycourt......... HO 5
HUdson............. HU 3,7&8
HUmboldt........... HU 6&9
HYde Park.......... HY 3

INdependence....... IN 3
INterocean......... IN 8
IRving............. IR 8

JUniper............ JU 3&8

KEdzie............. KE 3
KEnwood............ KE 6&8
KEystone........... KE 3&9
KIldare............ KI 5

LAfayette.......... LA 1,2&3
LAkeview........... LA 5&8
LAwndale........... LA 1&2
LIncoln............ LI 9
LIvingston......... LI 8
LOngbeach.......... LO 1
LUdlow............. LU 2&5

MAnsfield.......... MA 6
MErrimac........... ME 7
MIchigan........... MI 2
MIdway............. MI 3
MIchell............ MI 6
MOhawk............. MO 4
MOnroe............. MO 6
MUlberry........... MU 5
MUseum............. MU 4

NAtional........... NA 2&5
NEvada............. NE 2&8
NEwcastle.......... NE 1
NOrmal............. NO 7

OAkland............ OA 4
OFficial........... OF 3
ORchard............ OR 3&6

PAlisade........... PA 5
PEnsacola.......... PE 6
PLaza.............. PL 2
POlice............. PO 5
POrtsmouth......... PO 7
PRescott........... PR 9
PRospect........... PR 6&8
PUllman............ PU 5

RAdcliffe.......... RA 3
RAndolph........... RA 6&7
RAvenswood......... RA 8
REgent............. RE 1&4
REliance........... RE 5
REpublic........... RE 7
ROckwell........... RO 2
ROdney............. RO 3
ROgers Park........ RO 1&4

SAcramento......... SA 2
SAginaw............ SA 1
SEeley............. SE 3&8
SHeldrake.......... SH 3
SOuth Chicago...... SO 8
SOuth Shore........ SO 8
SPaulding.......... SP 2
SPring............. SP 4,5&7
STate.............. ST 1&2
STewart............ ST 3
SUnnyside.......... SU 4
SUperior........... SU 7

TAylor............. TA 9
TRiangle........... TR 3&4
TUxedo............. TU 9

UNderhill.......... UN 7
UNiversity......... UN 4,6&9
UPtown............. UP 8

VAn Buren.......... VA 6
VIctory............ VI 2
VIncennes.......... VI 6
VIrginia........... VI 7

WAbash............. WA 2
WAgner............. WA 4
WAlbrook........... WA 5
WAterfall.......... WA 8
WEather............ WE 4
WEbster............ WE 9
WEllington......... WE 5
WEntworth.......... WE 6
WHitehall.......... WH 3&4

YArds.............. YA 7

The fifth and final telephone number scheme began with the conversion to All Number Calling (ANC) on September 11, 1960.  Despite some early opposition from individuals and businesses who wanted to retain their beloved exchange prefixes, this evolutionary process was finally completed in 1977.

At that point, the Chicago alphabetical directory (White Pages) showed all local numbers in the city to be in the now familiar 7-digit format still in use today (such as, “236-1234”).

Exchange names continued to show up in some Chicago Yellow Pages and advertisements into the 1980s.

In the original North American Numbering Plan of 1947, all of the Chicago area was covered by area code 312, the rest of northern Illinois was 815, central Illinois was 217, and southern Illinois was 618.

By William D. Caughlin
Edited by Neil Gale, Ph.D. 

12 comments:

  1. Our Chicago number in the 1950s was HUmboldt 9-3639. That exchange does not show up here.

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  2. HUmboldt 9 and 6 are both on the list.

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  3. Our number was 651-####, what could that have been?

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  4. Our number was Hy3-2554 Jackson Park Highlands

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  5. We lived at the Belmont Hotel. Our number was BI 8-3400. Bitterseet 8.

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  6. My Dad's company used GLADSTONE-5 & LUDLOW-5. Business was located near 63rd, between Harlem & Oak Park. Area called the Clearing District, I think.???

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  7. My phone # from the 1950 DE 7-4987. I lived on the Near North Side of Chicago.

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  8. In Maywood the exchange FIlmore seems to conflict with the Chicago exchange FInancial.

    ReplyDelete
  9. Lincolin carpet used their number well in to the 80's "call NAtional2-9000..."

    ReplyDelete
  10. Very nice post. I absolutely love this site. Keep it up!

    ReplyDelete

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