| Surnames | Time Period | Researcher |
| Sanders | . | Richard Russell |
| Sandlian | 1900 | Courtney Storck |
| Saunders | 1930 - 1994 | Mary E. Hunt |
| Scarth | 1868 - 1902 | Judson Crow, Sr. |
| Schaefer | 1893 | Marie J. Hurlbut Fisher |
| Schenebricker | 1880’s - 1920’s | Kristin Fetzer |
| Scherger | 1880 - 1920 | Laura Cooksey |
| Schneider | 1800 - 1950 | Cathy Faass |
| Schober | 1870's - 1900 | Michael Hamersky |
| Schroyer | . | Lori Klassen |
| Schuchman | . | Houstin R. Hutton |
| Schwartz | 1850 - 1990's | David Kersting |
| Scobee | 1915 | Lori Klassen |
| Scott | 1908 | Ila Morrill |
| Scott | 1887 | Deb Shillo |
| Scroggins | 1965 - 1999 | Chuck Lowe |
| Sealock | 1800 - now | Denise Koch |
| Searl | 1940 - 1960 | Jeanette Cox Searl |
| Secoy | 1889 - 1920 | Betty Irby |
| Seidenfaden | 1850 - 1900 | Dave Johnson |
| Seisum | 1850 - now | Thomas Seisum |
| Seiwert | 1870 - 1999 | Douglas B. Ayer |
| Selvage | ? - now | Amanda Selvage |
| Senn | 1887 | Kathryn Bryant |
| Seward | 1900 - 1940 | Phyllis Solter |
| Shaw | 1900 - 1910 | Shaw |
| Sheldon | 1888 - 1902 | JP Humphrey |
| Shepherd | 1900's | Judy |
| Shields | 1992 | Glenn Baker |
| Shipps | 1920 - ? | Raylene |
| Shockey | . | Dan Smith |
| Shockey | 1850 - 1990 | David Kersting |
| Shufelberger | 1873 - 1920 | Lorna Rust |
| Shumate | 1966 - now | Lisa Clancy |
| Sickler | 1860 - now | Gail J. Crum Henderson-Wishnefsky |
| Sigler | 1920 - 1990 | Marilyn Swanson |
| Silks | 1860 - now | Jan Rowan |
| Silvey | Julie Willie | |
| Simmons | 1900 - 1930 | Patricia Reynolds Oeser |
| Simone | 1940 - 1950 | Teresa Simone |
| Sims | 1880 - ? | Loretta Ferriss |
| Sims | ? - 1916 | Beth Workman |
| Skinner | 1910 - now | Lori Parks |
| Skinner | 1930 - 1950 | Eldon (Ike) Stanley |
| Skinner | 1880 - 1910 | Nancy Kanatzar |
| Slattery | 1918 - 1970 | Ben Millar |
| Slusser | 1914 | John Knox |
| Slusser | 1870 - now | Randy Slusser |
| Smiley | 1922 - 1940 | Harold "Phil" Smiley |
| Smith | 1894 - 1918 | Delores Mather |
| Smith | 1910 - 1915 | Laurie Lewis |
| Smith | c1870 - ? | Roger Smith |
| Snodgrass | 1930 - 1955 | Tommy Holland |
| Solter | 1874 - now | Phyllis Solter |
| Somers | . | Marie Godwin LaDuron |
| Sommer | 1890 - 1920 | Erika Jones |
| Sonderup | 1890 - now | Leif Geilman |
| Songer | 1902 - 1930 | Evana Songer |
| Spencer | 1930 - 1995 | Mary E. Hunt |
| Spelts | 1900 - 1921 | Alice Deaton |
| St. Clair | 1910 - 1930 | Billy Ringwald |
| Stancer | 2000 | Marianne Spencer |
| Stanley | 1900 - 1999 | Ike Stanley |
| Stanley | 1901 - 1915 | Ruth Kuntz |
| Stanton | 1890 - now | Terry Row |
| Starr | 1850 - 1898 | MK Moreland |
| Startzman | 1800 - 1960 | Carolyn Startzman Johnson |
| Staton | 1920 - 1930 | Carole Linderoth |
| Steck | 1890 - 1920s | Patty James |
| Steele | 1870 - 1950 | Galen Lewis Steele Jr |
| Stehwein | 1930 - 1950 | Laralea Stehwein Whetstine |
| Stephenson | 1945 | Lynda Prine |
| Stevens | 1900 - now | Bobby Dobbins Title |
| Stewart | 1895 - 1902 | Lynne Sutton |
| Stewart | . | Suzanne Deal Sellers |
| Stites | 1830 - now | Charlene Hardin |
| Stone | 1905 - 1908 | Dori Stewart |
| Storck | 1880 - now | Courtney Storck |
| Stover | c1870 - ? | Treisa Dugas |
| Straight | c1904 - 1930 | Kathleen |
| Streiff | David O. Streiff | |
| Stroot | 1800 - now | Sylvester Stroot |
| Stuck | 1879 - 1893 | Judy Stuck |
| Stuckey | 1876 - now | Michael R. Stuckey |
| Stufflebeam | . | WA7ERY |
| Stull | 1920 - 1960 | Ben Millar |
| Sublett | before 1996 | Patricia Dill |
| Sudduth | 1900 - 1939 | Jennie Wright |
| Sullivan | . | Teresa Church |
| Summers | 1870 - 1910 | John S. Thomas |
| Sutherland | 1860 - now | Wilma Sinnott |
| Swaney | 1968 | Michael D. Swaney |
| Swartz | 1920's - 1970 | Iletta Swartz Pulley |
| Swartz | 1904 - 1924 | Michael Wiles |
| Tabler | 1877 - 1930 | Stephen M. Andrews |
| Talbott | 1900 - now | James Robert Talbott |
| Tarrant | 1900 - now | Jim Tarrant |
| Taylor | 1907 - 1946 | Lois Almeda |
| Taylor | 1840 - 1860 | Leslie Davis |
| Taylor | 1800 -1910 | Joann |
| Ten Eyck | 1800 - now | Linda Bonnell |
| Terhune | c1870 | Jim Terhune |
| Thomas | 1880 - 1900 | Mike Cooper |
| Thompson | 1900 - now | Shirley E. Johnson |
| Thrawl | 1880 - now | Donna Yates |
| Thrift | 1900 - 1960 | Cheryl Behrend |
| Timbers | c1942 - ? | Jayne Genter |
| Tolbert | 1911 - 1968 | Debby Chenoweth |
| Tomman | 1890 - 1920 | Paula Swope |
| Tregellas | 1880 - now | Susan Hatfield |
| Trego | 1870 - 1899 | William K. Hall |
| Trimmell | 1935 - now | Sharon Pierpont |
| Troy | . | Marie Godwin LaDuron |
| Tucker | 1879 - c1900 | Don Henricks |
| Turner | 1910 - 1920 | Laurie Lewis |
| Turner | 1875 - now | Stephen Carlile |
| Turner | 1937 - 1938 | Doyle Ekey |
| Tyree | . | TeaBird |