(I finally got a chance to do this.) Hopefully, this cluttered chart answers why WGST can't do anything to increase it's power.
Print it out.
STATIONS ON 640 AM
Call Specs Distance/Dir City
WGST 50kwD,1kwN,DA-2 3.2 mi./273° Atlanta, GA
WXSM 10kwD,810wN,DA-N 221.4 mi./030° Blountville, TN
WCRV 50kwD,480wN,DA-N 325.1 mi./287° Collierville, TN
WFNC 10kwD,1kwN 325.2 mi./072° Fayetteville, NC
WVLG 930wD,860wN 365.5 mi./156° Wildwood, FL
KTIB 5kwD,1kwN,DA-2 468.3 mi./237° Thibodaux, LA
WHLO 5kwD,500wN,DA-2 528.4 mi./016° Akron, OH
WMEN 7.5kwD,460wN,DA-2 541.0 mi./152° Royal Palm Beach, FL
WMEN(CP) 50kwD,25kwN,DA-2 545.0 mi./155° Boca Raton, FL
WMFN 1.2kwD,230wN 632.1 mi./353° Zeeland, MI
WWJZ 50kwD,950wN,DA-2 687.1 mi./048° Mount Holly, NJ
CFMJ 50kwU,DA 704.6 mi./021° Richmond Hill, ON
WWLS 5kwD,1kwN,DA-2 753.4 mi./282° Moore, OK
WOI 5kwD,1kwN,DA-N 761.6 mi./321° Ames, IA
WNNZ 50kwD,1kwN,DA-2 860.4 mi./044° Westfield, MA
CFOB 1kwU,DA-N 1127.6 mi./338° Fort Frances, ON
XENQ 10kwU 1275.8 mi./226° Tulancingo, Mexico
XENQ1 50kwD,10kwN,DA 1282.4 mi./226° Tulancingo, Mexico
XEWM 1kwU 1283.3 mi./206° SouthCristobal de Las C, Mexico
XEWM1 1kwU 1283.9 mi./206° SouthCristobal de Las C, Mexico
XEJUA 500wU 1289.4 mi./270° Cd.Juarez, Mexico
XEYQ1 5kwD,1kwN 1336.9 mi./241° Fresnillo, Mexico
XEHHI 25kwD,1kwN 1353.3 mi./255° Hidalgo del Parral, Mexico
XESRD 10kwD,100wN 1397.1 mi./250° Santiago Papasquiaro, Mexico
XEHDL 1kwU 1379.8 mi./220° Huajuapan de Leon, Mexico
KGVW 10kwD,1kwN,DA-2 1638.7 mi./308° Belgrade, MT
CBN 10kwU 1893.8 mi./050° Saint John's, NFo
KFI 50kwU 1922.6 mi./280° Los Angeles, CA