There are three files to download per quad:
xxxxxx.sdw
xxxxxx.sid
xxxxxx.txt

Click here for DRG's

Click here for DOQQ's
3188A4 BROWN TOWN
3188A5 VERNAL
3188A6 LEAKESVILLE SW
3188A7 MCLAIN
3188A8 TAYLOR HILL
3188B4 ROUNSAVILLE
3188B5 LEAKESVILLE
3188B6 JONATHAN
3188B7 NEELY
3188B8 BEAUMONT
3188C4 FRUITDALE
3188C5 CLARK
3188C6 AVERA
3188C7 BREWER
3188C8 RICHTON
3188D4 STATE LINE
3188D5 KNOBTOWN
3188D6 PIAVE
3188D7 MULBERRY
3188D8 RHODES
3188E4 COPELAND
3188E5 BUCKATUNNA
3188E6 CLARA
3188E7 WATER OAK
3188E8 STRENGTHFORD
3188F4 AQUILLA
3188F5 DENHAM
3188F6 WAYNESBORO
3188F7 WHISTLER
3188F8 MYRICK
3188G4 ISNEY
3188G5 MATHERVILLE
3188G6 SHUBUTA
3188G7 EUCUTTA
3188G8 HEIDELBERG SW
3188H4 MELVIN
3188H5 CARMICHAEL
3188H6 DE SOTO
3188H7 HALE
3188H8 HEIDELBERG