- Geological Survey (U.S.), 1974, Hydrologic Unit Map -- 1974, Georgia: Hydrologic Unit 10, 1 map : col. ; 104 x 94 cm. fold. in envelope 30 x 24 cm; An overprint of the 1:500,000-scale state base map. Shows counties, location, and names of all cities and towns and most of the smaller settlements and railroads in black; water features in blue; hydrologic boundaries and codes in red; county codes in green. No contours. Sheet 39 by 45 inches. 1970 base.,
- Geological Survey (U.S.), 1974, Hydrologic Unit Map -- 1974, Hawaii: Hydrologic Unit 11, 1 map : col. ; 84 x 124 cm. fold. in envelope 30 x 24 cm.; An overprint of the 1:500,000-scale state base map. Shows counties, location, and names of all cities and towns and most of the smaller settlements and railroads in black; water features in blue; hydrologic boundaries and codes in red; county codes in green. No contours. Sheet 35 by 51 inches. 1971 base.,
- Geological Survey (U.S.), 1974, Hydrologic Unit Map -- 1974, Idaho: Hydrologic Unit 12, col. map 162 x 145 cm. fold. in envelope 30 x 24 cm.; An overprint of the 1:500,000-scale state base map. Shows counties, location, and names of all cities and towns and most of the smaller settlements, railroads, and township and range lines in black; water features in blue; hydrologic boundaries and codes in red; county codes in green. No contours. Sheet 43 by 66 inches. 1964 base.,
- Geological Survey (U.S.), 1974, Hydrologic Unit Map -- 1974, Illinois: Hydrologic Unit 13, col. map 126 x 74 cm. fold. in envelope 30 x 24 cm.; Reprint 1988; An overprint of the 1:500,000-scale state base map. Shows counties, location, and names of all cities and towns and most of the smaller settlements, railroads, and township and range lines in black; water features in blue; hydrologic boundaries and codes in red; county codes in green. No contours. Sheet 31 by 52 inches. 1972 base.,
- Geological Survey (U.S.), 1974, Hydrologic Unit Map -- 1974, Indiana: Hydrologic Unit 14, 1 map. : col. ; 91 x 59 cm. fold. in envelope 30 x 24 cm.; An overprint of the 1:500,000-scale state base map. Shows counties, location, and names of all cities and towns and most of the smaller settlements, railroads, and township and range lines in black; water features in blue; hydrologic boundaries and codes in red; county codes in green. No contours. Sheet 32 by 41 inches. 1950 base.,
- Geological Survey (U.S.), 1974, Hydrologic Unit Map -- 1974, Iowa: Hydrologic Unit 15, col. map 75 x 112 cm. fold. in envelope 30 x 24 cm.; An overprint of the 1:500,000-scale state base map. Shows counties, location, and names of all cities and towns and most of the smaller settlements, railroads, and township and range lines in black; water features in blue; hydrologic boundaries and codes in red; county codes in green. No contours. Sheet 33 by 46 inches. 1974 base.,
- Geological Survey (U.S.), 1974, Hydrologic Unit Map -- 1974, Kansas: Hydrologic Unit 16, col. map 72 x 149 cm. fold. in envelope 30 x 24 cm.; An overprint of the 1:500,000-scale state base map. Shows counties, location, and names of all cities and towns and most of the smaller settlements, railroads, and township and range lines in black; water features in blue; hydrologic boundaries and codes in red; county codes in green. No contours. Sheet 31 by 60 inches.,
- Geological Survey (U.S.), 1974, Hydrologic Unit Map -- 1974, Kentucky: Hydrologic Unit 17, 1 map : col. 63 x 139 cm. fold. in envelope 30 x 24 cm.; Reprint 1988; An overprint of the 1:500,000-scale state base map. Shows counties, location, and names of all cities and towns and most of the smaller settlements in black; water features in blue; hydrologic boundaries and codes in red; county codes in green. No contours. Sheet 27 by 56 inches.,
- Geological Survey (U.S.), 1974, Hydrologic Unit Map -- 1974, Louisiana: Hydrologic Unit 18, 1 map : col. ; 100 x 106 cm.; Reprint 1997; An overprint of the 1:500,000-scale state base map. Shows counties, location, and names of all cities and towns and most of the smaller settlements, railroads, and township and range lines in black; water features in blue; hydrologic boundaries and codes in red; county codes in green. No contours. Sheet 41 by 45 inches.,
- Geological Survey (U.S.), 1974, Hydrologic Unit Map -- 1974, Maine: Hydrologic Unit 19, 1 map : col. ; 101 x 69 cm.; Reprint 1980; An overprint of the 1:500,000-scale state base map. Shows counties, location and names of all cities and towns and most of the smaller settlements, and railroads in black; water features in blue; hydrologic boundaries and codes in red; county codes in green. No contours. Sheet 30 by 44 inches. 1958 base.,
- Geological Survey (U.S.), 1974, Hydrologic Unit Map -- 1974, states of Massachusetts, Rhode Island and Connecticut: Hydrologic Unit 21, 1 map : col. ; 49 x 93 cm.; Reprint 1989; An overprint of the 1:500,000-scale state base map. Shows counties, location and names of all cities and towns and most of the smaller settlements, railroads, and township and range lines in black; water features in blue; hydrologic boundaries and codes in red; county codes in green. No contours. Sheet 22 by 39 inches.,
- Geological Survey (U.S.), 1974, Hydrologic Unit Map -- 1974, Minnesota: Hydrologic Unit 23, 1 map : col. ; 136 x 120 cm. fold. in envelope 30 x 24 cm.; An overprint of the 1:500,000-scale state base map. Shows counties, location and names of all cities and towns and most of the smaller settlements, railroads, and township and range lines in black; water features in blue; hydrologic boundaries and codes in red; county codes in green. No contours. Sheet 50 by 57 inches.,
- Geological Survey (U.S.), 1974, Hydrologic Unit Map -- 1974, Mississippi: Hydrologic Unit 24, col. map 115 x 70 cm. fold. in envelope 30 x 24 cm.; An overprint of the 1:500,000-scale state base map. Shows counties, location and names of all cities and towns and most of the smaller settlements, railroads, and township and range lines in black; water features in blue; hydrologic boundaries and codes in red; county codes in green. No contours. Sheet 29 by 48 inches.,
- Geological Survey (U.S.), 1974, Hydrologic Unit Map -- 1974, Nebraska: Hydrologic Unit 27, col. map 73 x 152 cm. fold. in envelope 30 x 24 cm.; An overprint of the 1:500,000-scale state base map. Shows counties, location and names of all cities and towns and most of the smaller settlements, railroads, and township and range lines in black; water features in blue; hydrologic boundaries and codes in red; county codes in green. No contours. Sheet 32 by 62 inches.,
- Geological Survey (U.S.), 1974, Hydrologic Unit Map -- 1974, Nevada: Hydrologic Unit 28, 1 map : col. ; 159 x 109 cm. fold. in envelope 30 x 24 cm.; An overprint of the 1:500,000-scale state base map. Shows counties, location and names of all cities and towns and most of the smaller settlements, and railroads in black; water features in blue; hydrologic boundaries and codes in red; county codes in green. No contours. Sheet 45 by 66 inches.,
- Geological Survey (U.S.), 1974, Hydrologic Unit Map -- 1974, New Hampshire and Vermont: Hydrologic Unit 29, 1 map : col. ; 61 x 69 cm.; Reprint 1988; An overprint of the 1:500,000-scale state base map. Shows state and county boundaries, location and names of all cities and towns and most of the smaller settlements, and railroads in black; water features in blue; hydrologic boundaries and codes in red; county codes in green. No contours. Sheet 29 by 30 inches.,
- Geological Survey (U.S.), 1974, Hydrologic Unit Map -- 1974, New Jersey: Hydrologic Unit 30, 1 map : col. ; 59 x 59 cm.; Reprint 1985; An overprint of the 1:500,000-scale state base map. Shows counties, location and names of all cities and towns and most of the smaller settlements, and railroads in black; water features in blue; hydrologic boundaries and codes in red; county codes in green. No contours. Sheet 26 by 28 inches. 1948 base.,
- Geological Survey (U.S.), 1974, Hydrologic Unit Map -- 1974, New Mexico: Hydrologic Unit 31, 1 map : col. ; 137 x 119 cm., folded in envelope 30 x 24 cm.; Reprint 1986; An overprint of the 1:500,000-scale state base map. Shows counties, location and names of all cities and towns and most of the smaller settlements, railroads, and township and range lines in black; water features in blue; hydrologic boundaries and codes in red; county codes in green. No contours. Sheet 49 by 57 inches.,
- Geological Survey (U.S.), 1974, Hydrologic Unit Map -- 1974, New York: Hydrologic Unit 32, col. map ; 106x137 cm.; Reprint 1996; An overprint of the 1:500,000-scale state base map. Shows counties, location and names of all cities and towns and most of the smaller settlements, and railroads in black; water features in blue; hydrologic boundaries and codes in red; county codes in green. No contours. Sheet 46 by 69 inches. 1953 base.,
- Geological Survey (U.S.), 1974, Hydrologic Unit Map -- 1974, North Carolina: Hydrologic Unit 33, 1 map : col. ; 64 x 161 cm.; Reprint 1986; An overprint of the 1:500,000-scale state base map. Shows counties, location and names of all cities and towns and most of the smaller settlements, and railroads in black; water features in blue; hydrologic boundaries and codes in red; county codes in green. No contours. Sheet 28 by 66 inches. 1974 base.,
- Geological Survey (U.S.), 1974, Hydrologic Unit Map -- 1974, North Dakota: Hydrologic Unit 34, 1 map : col. ; 134 x 75 cm. fold. in envelope 30 x 24 cm.; An overprint of the 1:500,000-scale state base map. Shows counties, location and names of all cities and towns and most of the smaller settlements, railroads, and township and range lines in black; water features in blue; hydrologic boundaries and codes in red; county codes in green. No contours. Sheet 33 by 55 inches. 1974 base.,
- Geological Survey (U.S.), 1974, Hydrologic Unit Map -- 1988, Ohio: Hydrologic Unit 35, 1 map : col. ; 85 x 94 cm. fold. in envelope 30 x 24 cm.; Reprint 1988; An overprint of the 1:500,000-scale state base map. Shows counties, location and names of all cities and towns and most of the smaller settlements, and railroads in black; water features in blue; hydrologic boundaries and codes in red; county codes in green. No contours. Sheet 40 by 37 inches. 1951 base.,
- Geological Survey (U.S.), 1974, Hydrologic Unit Map -- 1974, Oklahoma: Hydrologic Unit 36, col. map 80 x 133 cm. fold. in envelope 30 x 24 cm.; An overprint of the 1:500,000-scale state base map. Shows counties, location and names of all cities and towns and most of the smaller settlements, railroads, and township and range lines in black; water features in blue; hydrologic boundaries and codes in red; county codes in green. No contours. Sheet 34 by 54 inches.,
- Geological Survey (U.S.), 1974, Hydrologic Unit Map -- 1974, Oregon: Hydrologic Unit 37, 1 map : col. ; 102 x 134 cm. fold. in envelope 30 x 24 cm.; An overprint of the 1:500,000-scale state base map. Shows counties, location and names of all cities and towns and most of the smaller settlements, railroads, and township and range lines in black; water features in blue; hydrologic boundaries and codes in red; county codes in green. No contours. Sheet 44 by 55 inches. 1974 base.,
- Geological Survey (U.S.), 1974, Hydrologic Unit Map -- 1974, Pennsylvania: Hydrologic Unit 39, 1 map : col. ; 62 x 120 cm., folded in envelope 30 x 24 cm.; An overprint of the 1:500,000-scale state base map. Shows counties, location and names of all cities and towns and most of the smaller settlements, and railroads in black; water features in blue; hydrologic boundaries and codes in red; county codes in green. No contours. Sheet 29 by 49 inches. 1953 base.,
- Geological Survey (U.S.), 1974, Hydrologic Unit Map -- 1974, state of South Carolina: Hydrologic Unit 40, 1 map : col. ; 73 x 92 cm.; Reprint 1990; An overprint of the 1:500,000-scale state base map. Shows counties, location and names of all cities and towns and most of the smaller settlements, and railroads in black; water features in blue; hydrologic boundaries and codes in red; county codes in green. No contours. Sheet 38 by 50 inches. 1970 base.,
- Geological Survey (U.S.), 1974, Hydrologic Unit Map -- 1974, South Dakota: Hydrologic Unit 41, col. map 92 x 129 cm. fold. in envelope 30 x 24 cm.; An overprint of the 1:500,000-scale state base map. Shows counties, location and names of all cities and towns and most of the smaller settlements, railroads, and township and range lines in black; water features in blue; hydrologic boundaries and codes in red; county codes in green. No contours. Sheet 39 by 52 inches.,
- Geological Survey (U.S.), 1974, Hydrologic Unit Map -- 1974, Tennessee: Hydrologic Unit 42, 1 map : col. ; 42 x 160 cm., on sheet 54 x 165 cm., folded in envelope 30 x 24 cm.; Reprint 1991,
- Geological Survey (U.S.), 1974, Hydrologic Unit Map -- 1974, Texas: Hydrologic Unit 43, 1 map on 4 sheets : col. ; 202 x 254 cm., sheets 107 x 132 cm. fold. in envelope 30 x 24 cm.; An overprint of the 1:500,000-scale state base map. Shows counties, location and names of all cities and towns and most of the smaller settlements, and railroads in black; water features in blue; hydrologic boundaries and codes in red; county codes in green. No contours. Four sheets. Each 42 by 52 inches.,
- Geological Survey (U.S.), 1974, Hydrologic Unit Map -- 1974, Utah: Hydrologic Unit 44, 1 map : col. ; 115 x 93 cm., folded in envelope 30 x 24 cm.; An overprint of the 1:500,000-scale state base map. Shows counties, location and names of all cities and towns and most of the smaller settlements, railroads, and township and range lines in black; water features in blue; hydrologic boundaries and codes in red; county codes in green. No contours. Sheet 42 by 58 inches. 1959 base.,
- Geological Survey (U.S.), 1974, Hydrologic Unit Map -- 1974, Virginia: Hydrologic Unit 46, 1 map : col. ; 68 x 152 cm. folded in envelope 30 x 24 cm.; Reprint 1985; ; An overprint of the 1:500,000-scale state base map. Shows counties, location and names of all cities and towns and most of the smaller settlements, and railroads in black; water features in blue; hydrologic boundaries and codes in red; county codes in green. No contours. Sheet 46 by 69 inches. 1973 base.,
- Geological Survey (U.S.), 1974, Hydrologic Unit Map -- 1974, Washington: Hydrologic Unit 47, col. map 87 x 124 cm. fold. in envelope 30 x 24 cm.; An overprint of the 1:500,000-scale state base map. Shows counties, location and names of all cities and towns and most of the smaller settlements, railroads, and township and range lines in black; water features in blue; hydrologic boundaries and codes in red; county codes in green. No contours. Sheet 38 by 51 inches. 1974 base.,
- Geological Survey (U.S.), 1974, Hydrologic Unit Map -- 1989, West Virginia: Hydrologic Unit 48, 1 map : col. ; 79 x 90 cm. fold. in envelope 30 x 24 cm.; Reprint 1989; An overprint of the 1:500,000-scale state base map. Shows counties, location and names of all cities and towns and most of the smaller settlements, and railroads in black; water features in blue; hydrologic boundaries and codes in red; county codes in green. No contours. Sheet 36 by 40 inches. 1963 base.,
- Geological Survey (U.S.), 1974, Hydrologic Unit Map -- 1974, Wisconsin: Hydrologic Unit 49, 1 map : col. ; 111 x 108 cm. fold. in envelope 30 x 24 cm.; An overprint of the 1:500,000-scale state base map. Shows counties, location and names of all cities and towns and most of the smaller settlements, railroads, and township and range lines in black; water features in blue; hydrologic boundaries and codes in red; county codes in green. No contours. Sheet 44 by 46 inches. 1968 base.,
- Geological Survey (U.S.), 1974, Hydrologic Unit Map -- 1974, Wyoming: Hydrologic Unit 50, 1 map : col. ; 95 x 136 cm. fold. in envelope 30 x 24 cm.; An overprint of the 1:500,000-scale state base map. Shows counties, location and names of all cities and towns and most of the smaller settlements, and railroads in black; water features in blue; hydrologic boundaries and codes in red; county codes in green. No contours. Sheet 41 by 56 inches.,
- Geological Survey (U.S.), 1974, Hydrologic Unit Map -- 1974, Caribbean region: Hydrologic Unit 58, 1 map : col. 39 x 122 cm. fold. in envelope 30 x 24 cm.; Reprint 1990; An overprint of the 1:240,000-scale base map. Shows location and names of all cities and towns and most of the smaller settlements and railroads in black; water features in blue; hydrologic boundaries and codes in red. No contours. Sheet 42 by 58 inches. 1952 base.,
- Geological Survey (U.S.), 1974, Hydrologic Unit Map -- 1974, Colorado: Hydrologic Unit 6, 1 map : col. ; 95 x 141 cm. folded in envelope 30 x 24 cm.; Reprint 1992; An overprint of the 1:500,000-scale state base map. Shows counties, location and names of all cities and towns and most of the smaller settlements, railroads, and township and range lines in black; water features in blue; hydrologic boundaries and codes in red; county codes in green. No contours. Sheet 41 by 58 inches.,
- Geological Survey (U.S.), 1974, Hydrologic Unit Map -- 1974, Florida: Hydrologic Unit 9, col. map 153 x 107 cm. fold. in envelope 30 x 24 cm.; Reprint 1985; An overprint of the 1:500,000-scale state base map. Shows counties, location and names of all cities and towns and most of the smaller settlements, railroads, and township and range lines in black; water features in blue; hydrologic boundaries and codes in red; county codes in green. No contours. Sheet 45 by 65 inches. 1974 base.,
