Bridges had an extensive correspondence with many of his contemporary brass players of the early 20th century, focusing on John Philip Sousa and Richard Pryor. At some point, an attempt was made to put letters to and from some individuals into separate folders. This was not completed, and these people had some letters in both their own folders and in the general correspondence. The current processor of this collection decided to combine Bridges correspondence, research queries and most of the individual folders into one series (Correspondence), arranged chronologically, with a listing of selected correspondents in each folder . Also included in the correspondence folders are such things as certificates, membership cards, and the occasional photograph.

At time went on, Bridges' interest expanded to include research on his pamphlet, Cornet Talks and culminated in his book, Pioneers in Brass (often referred to as "P.I.B." in the letters) and its subsequent revisions and reprinting. Beginning in the 1940s or earlier Bridges' began to reformat music from his large collection of early recordings onto tape and sell them. Orders for these "on-demand" tapes were included in the correspondence. Before 1964, when the book was first published, orders for the book and tapes were mixed in with the general correspondence. Orders for both the tapes and his publications often developed into lengthy exchanges of letters, and became research documents as well as correspondence. Beginning in 1964, the routine orders for his publications and tapes were placed in Series 2 - Orders.

There are some folders with materials relating to Bridges' research into specific individuals. If these materials could not be related to a specific letter in the general correspondence as, for example, death certificates or music programs, they were left in their folders and were filed in Series 3 - Research.

Correspondence regarding the printing, binding, publication, advertising and other activities relating to his book and pamphlet are in Series 4 - Printing.

Bridges kept carbon copies of some outgoing letters, but many of these do not have the name of the recipient, with most being addressed as "Dear Friend". If the name could be determined, the processor included it within brackets above the salutation. If the recipient answered Bridges' letter on the back, or below Bridges' text, the letter is filed under the later date of the response if known. If not, it is filed under the date of the outgoing letter.

Those correspondents who were represented by separate folders are listed below. The dates indicate the contents of those separate folders, but there may have been other letters in the general correspondence outside the date range indicated. The separate folders were for:

Ed Bahr (1975-1978) Harold B. Bachman (1916-1972) H. T. Brasch (mainly 1943-1948) Paul Bierley (1926-2016) His letters date from 1960 to 1976. Many of these letters are from Bridges to Bierley and were donated by Mr. Bierley in 1989 to the ITA archives. They have been interfiled in the general correspondence folder. Jaroslav (Jerry) Cimera (mainly 1924, 1943-1957) Edwin Clarke (mainly 1915-1917) Ernest Clarke (1922-1941) Herbert Lincoln Clarke (1867- 1945) - Letters from 1916-1948. Robert Clarke (1924-1933) Merle Evans (1930-1973) Ernest B. Fox ("E.B.") (1940s-1950s, including letters between Fox and Frank McGrann as well as with Glenn D. Bridges) Patrick S. Gilmore (1968-1971) Norman Henckel (1966-1973) Ward Hodge (d. October 27, 1980) - His letters date mainly from the 1960s to 1980. John Horn (1915, 1923) Joseph Huber (1928-1949) and later with his widow, Flora Paul Jackson, nephew of Glenn D. Bridges Eugene (Gene) La Barr (1888-October 19, 1956) - His letters date mainly from 1952 to 1956, with a few from his widow, Flora, in 1957. Arthur W. (Art) Lehman (September 24, 1917 - June 19, 2009) did not have a separate folder but was a longtime correspondent from 1944 onwards. Cliff Lillya (did not have a separate folder but was a longtime correspondent) Frank McGrann (d. 1961)-Letters from 1943-1961, including letters between McGrann and Ernest B. Fox as well as with Glenn D. Bridges. His son, John McGrann, informed Bridges of his father's death in a letter of June, 1964. He mentions enclosing some correspondence of possible interest to Bridges. This is most probably the source of the letters between McGrann and E.B. Fox. After Glenn's death in December of 1981, his widow Althea M. Bridges continued the correspondence and the book sales, although the recordings ceased.