So sad that only eight of our single letter chapters are still active.
Alpha (1902) - Miami University of Ohio
Beta (1908) - Cornell (inactive since 1932)
Gamma (1923) - Minnesota (inactive since 1965)
Delta (1909) - DePauw
Epsilon (1909) - Indiana University
Zeta (1910) - University of Nebraska (inactive since 1971)
Eta (1910) - Baker (inactive since 1934)
Theta (1911) - Ohio State
Iota (1913) - University of Iowa (recolonized 2002)
Kappa (1914) - University of Washington
Lambda (1915) - Kansas (inactive since 1976)
Mu (1915) - Cal Berkeley (inactive since 1969)
Nu (1915) - Knox (inactive since 1964)
Xi (1916) - University of Cincinnati (inactive since 1977)
Omicron (1916) - University of Pittsburgh (my chapter!!!

)
Pi (1917) - Eureka College
Rho (1917) - University of Denver
Sigma (1917) - Louisiana State University
Tau (1918) - Wisconsin (inactive since 1971)
Upsilon (1919) - North Dakota (inactive since 1988)
Phi (1919) - Washington State (inactive since 1958)
Chi (1919) - Oregon State (inactive since 1977)
Psi (1920) - Franklin (inactive since 1990)
Omega (1920) - Oregon (inactive)
Sharp-eyed readers will notice that, although the University of Minnesota chapter is designated "Gamma", it was actually installed in 1923; years after the rest of the single-letter chapters. I don't remember why this is, though, so if any Delta Zetas know, feel free to chime in!