diff --git a/constants.asm b/constants.asm
index 0b24ea05..1e3960d6 100644
--- a/constants.asm
+++ b/constants.asm
@@ -30,3 +30,4 @@ INCLUDE "constants/credits_constants.asm"
 INCLUDE "constants/music_constants.asm"
 INCLUDE "constants/tilesets.asm"
 INCLUDE "constants/starter_mons.asm"
+INCLUDE "constants/map_location_constants.asm"
diff --git a/constants/map_location_constants.asm b/constants/map_location_constants.asm
new file mode 100644
index 00000000..22df77c8
--- /dev/null
+++ b/constants/map_location_constants.asm
@@ -0,0 +1,55 @@
+PalletTown_LOCATION	EQU $00
+ViridianCity_LOCATION	EQU $01
+PewterCity_LOCATION	EQU $02
+CeruleanCity_LOCATION	EQU $03
+LavenderTown_LOCATION	EQU $04
+VermilionCity_LOCATION	EQU $05
+CeladonCity_LOCATION	EQU $06
+FuchsiaCity_LOCATION	EQU $07
+CinnabarIsland_LOCATION	EQU $08
+IndigoPlateau_LOCATION	EQU $09
+SaffronCity_LOCATION	EQU $0a
+Route1_LOCATION	EQU $0b
+Route2_LOCATION	EQU $0c
+Route3_LOCATION	EQU $0d
+Route4_LOCATION	EQU $0e
+Route5_LOCATION	EQU $0f
+Route6_LOCATION	EQU $10
+Route7_LOCATION	EQU $11
+Route8_LOCATION	EQU $12
+Route9_LOCATION	EQU $13
+Route10_LOCATION	EQU $14
+Route11_LOCATION	EQU $15
+Route12_LOCATION	EQU $16
+Route13_LOCATION	EQU $17
+Route14_LOCATION	EQU $18
+Route15_LOCATION	EQU $19
+Route16_LOCATION	EQU $1a
+Route17_LOCATION	EQU $1b
+Route18_LOCATION	EQU $1c
+Route19_LOCATION	EQU $1d
+Route20_LOCATION	EQU $1e
+Route21_LOCATION	EQU $1f
+Route22_LOCATION	EQU $20
+Route23_LOCATION	EQU $21
+Route24_LOCATION	EQU $22
+Route25_LOCATION	EQU $23
+ViridianForest_LOCATION	EQU $24
+MountMoon_LOCATION	EQU $25
+RockTunnel_LOCATION	EQU $26
+SeaCottage_LOCATION	EQU $27
+SSAnne_LOCATION	EQU $28
+PokemonLeague_LOCATION	EQU $29
+UndergroundPath_LOCATION	EQU $2a
+PokemonTower_LOCATION	EQU $2b
+SeafoamIslands_LOCATION	EQU $2c
+VictoryRoad_LOCATION	EQU $2d
+DiglettsCave_LOCATION	EQU $2e
+RocketHQ_LOCATION	EQU $2f
+SilphCo_LOCATION	EQU $30
+PokemonMansion_LOCATION	EQU $31
+SafariZone_LOCATION	EQU $32
+CeruleanCave_LOCATION	EQU $33
+PowerPlant_LOCATION	EQU $34
+
+NUM_LOCATIONS EQU $35
diff --git a/data/town_map_entries.asm b/data/town_map_entries.asm
index d2edd949..c46c2c50 100755
--- a/data/town_map_entries.asm
+++ b/data/town_map_entries.asm
@@ -99,3 +99,66 @@ InternalMapEntries: ; 71382 (1c:5382)
 	IMAP $ED,$A,$5,SilphCoName
 	IMAP $F8,$0,$2,PokemonLeagueName
 	db $FF
+
+MapToLocationIndexTable:
+	db $29,PalletTown_LOCATION
+	db $2E,ViridianCity_LOCATION
+	db $33,Route2_LOCATION
+	db $34,ViridianForest_LOCATION
+	db $3B,PewterCity_LOCATION
+	db $3E,MountMoon_LOCATION
+	db $44,CeruleanCity_LOCATION
+	db $45,Route4_LOCATION
+	db $46,CeruleanCity_LOCATION
+	db $49,Route5_LOCATION
+	db $4C,Route6_LOCATION
+	db $4F,Route7_LOCATION
+	db $51,Route8_LOCATION
+	db $53,RockTunnel_LOCATION
+	db $54,PowerPlant_LOCATION
+	db $57,Route11_LOCATION
+	db $58,Route12_LOCATION
+	db $59,SeaCottage_LOCATION
+	db $5F,VermilionCity_LOCATION
+	db $69,SSAnne_LOCATION
+	db $6D,VictoryRoad_LOCATION
+	db $77,PokemonLeague_LOCATION
+	db $78,UndergroundPath_LOCATION
+	db $79,PokemonLeague_LOCATION
+	db $7A,UndergroundPath_LOCATION
+	db $8D,CeladonCity_LOCATION
+	db $8E,LavenderTown_LOCATION
+	db $95,PokemonTower_LOCATION
+	db $98,LavenderTown_LOCATION
+	db $9C,FuchsiaCity_LOCATION
+	db $9D,SafariZone_LOCATION
+	db $9F,FuchsiaCity_LOCATION
+	db $A3,SeafoamIslands_LOCATION
+	db $A4,VermilionCity_LOCATION
+	db $A5,FuchsiaCity_LOCATION
+	db $A6,PokemonMansion_LOCATION
+	db $AE,CinnabarIsland_LOCATION
+	db $AF,IndigoPlateau_LOCATION
+	db $B8,SaffronCity_LOCATION
+	db $BA,Route15_LOCATION
+	db $BD,Route16_LOCATION
+	db $BE,Route12_LOCATION
+	db $C0,Route18_LOCATION
+	db $C1,SeafoamIslands_LOCATION
+	db $C2,Route22_LOCATION
+	db $C3,VictoryRoad_LOCATION
+	db $C4,Route12_LOCATION
+	db $C5,VermilionCity_LOCATION
+	db $C6,DiglettsCave_LOCATION
+	db $C7,VictoryRoad_LOCATION
+	db $CF,RocketHQ_LOCATION
+	db $D6,SilphCo_LOCATION
+	db $D9,PokemonMansion_LOCATION
+	db $E2,SafariZone_LOCATION
+	db $E5,CeruleanCave_LOCATION
+	db $E6,LavenderTown_LOCATION
+	db $E7,CeruleanCity_LOCATION
+	db $E9,RockTunnel_LOCATION
+	db $ED,SilphCo_LOCATION
+	db $F8,PokemonLeague_LOCATION
+	db $FF
diff --git a/engine/town_map.asm b/engine/town_map.asm
index 9e5eb827..1db61873 100755
--- a/engine/town_map.asm
+++ b/engine/town_map.asm
@@ -563,6 +563,21 @@ Func_712f1: ; 712f1 (1c:52f1)
 	ld l, a
 	ret
 
+MapToLocationIndex:
+	cp REDS_HOUSE_1F
+	ret c
+	ld hl, MapToLocationIndexTable
+.loop
+	cp [hl]
+	jr c, .found
+	inc hl
+	inc hl
+	jr .loop
+.found
+	inc hl
+	ld a, [hl]
+	ret
+
 INCLUDE "data/town_map_entries.asm"
 
 INCLUDE "text/map_names.asm"
diff --git a/wram.asm b/wram.asm
index c07b3dab..af8a4b43 100755
--- a/wram.asm
+++ b/wram.asm
@@ -1286,7 +1286,6 @@ wPokedexSeen:: ; d30a
 	flag_array NUM_POKEMON
 wPokedexSeenEnd::
 
-
 wNumBagItems:: ; d31d
 	ds 1
 wBagItems:: ; d31e
@@ -2115,6 +2114,9 @@ SECTION "Empty", WRAMX, BANK[1]
 
 wPokemonlessBlackout:: ds 1
 
+wHadEncounterInLocation::
+	flag_array NUM_LOCATIONS
+
 SECTION "Stack", WRAMX[$dfff], BANK[1]
 wStack:: ; dfff
 	ds -$100