Today marks the 50th anniversary of the March on Washington for Jobs and Freedom, during which Dr. Martin Luther King, Jr. delivered his famous “I Have a Dream” speech. The march was held on Wednesday, August 28th, 1963 and the Big Three television networks were there to cover it. According to an article in the August 19th, 1963 issue of Broadcasting, the networks met on August 14th and agreed to pool their coverage, with CBS in charge and 22 cameras in play. Art Kane of CBS-TV would serve as pool producer. At the time, plans by network were said to be in flux .
The following week, Broadcasting reported more firm plans by network:
ABC-TV will have a minimum of two-and-one-half hours coverage: 9:30-9:45 a.m., five minutes every half hour from 10 a.m. until noon, 12 noon-12:30, 2-2:30 and 4:30-5 p.m. The regular Ron Cochrane newscast will orginate from Washington for broadcast between 6-7 p.m., and a special wrapup will be aired 11:15-11:45 p.m.
CBS-TV also will have a minimum of two-and-one-half hours coverage including Calendar (10-10:30 a.m.), 12 noon-12:25 p.m., a half-hour report from the Lincoln memorial and 7:30-8:30 p.m. wrapup with Walter Cronkite.
NBC-TV is planning 100 minutes of coverage: 2-2:25 p.m., 4:30-5 p.m. and an 11:15-12 midnight wrapup. 
On the day of the march, The New York Times published its own rundown of network coverage:
The Columbia Broadcasting System has scheduled three television programs to be broadcast live from Washington–at 10 A.M., 11:30 and a time in the afternoon. A program of taped highlights will be shown at 7:30 P.M.
The National Broadcasting Company has scheduled programs for 8:30 A.M., 11:30, 2 P.M. and 4:30. Taped highlights will be shown at 11:15 P.M.
The American Broadcasting Company will broadcast from the scene at 9:30 A.M., 11:30, 2 P.M. and 4:30 and will carry taped highlights at 11:15 P.M. 
The following day, Val Adams of The New York Times recapped the network coverage, writing that ABC was the first to start live coverage at 11:16AM followed by CBS and NBC at 11:30AM. According to Adams, “the coverage turned out to be longer than had been anticipated” . He noted that between the three networks, viewers were able to watch from 11:15AM-12:45PM and from 1:30-4:30PM, with CBS the only network to broadcast continuously from 1:30-4:30PM, at which time ABC and NBC presented taped highlights.
Because so much of the television coverage of the march was live, it is impossible to know based on television listings what each of the networks aired on August 28th, 1963. Other than the 7:30-8:30PM CBS special, there does not appear to have been any prime time programming on the networks dedicated to the march.
What remains of the network coverage of the historic march? The NBCUniversal Archives include film footage of the march as well as a 90-minute special broadcast from 4:30-6PM, some of which can be seen below (it has been either cropped or stretched to fit a 16:9 aspect ratio):
The UCLA Film & Television Archive has a 43-minute NBC news special recapping the march, anchored by Frank McGee, likely the 11:15PM-12AM taped highlights. UCLA also has 142 minutes of ABC coverage, including special reports from 9:30-9:48AM, 10-10:02AM, 10:28-10:42AM and 52 minutes of pool coverage from the post-march program held at the Lincoln Memorial.
The Paley Center for Media has a significant amount of CBS coverage in its collection, much of it unidentified, which if not duplicated totals more than seven hours of footage. The only identified footage is almost three hours from 1:30-4:30PM.
Local stations, both in Washington, D.C. and across the country, also covered the march. Radio stations covered the march as well, including those affiliated with the Educational Radio Network. It aired 15 hours of coverage, which can be found at the WGBH Open Vault.
2 “Radio-TV plans D.C. march coverage.” Broadcasting. 26 Aug. 1963: 57.
3 “TV and Radio Slate Rights March Shows.” New York Times. 28 Aug. 1963: 21.
4 Adams, Val. “TV: Coverage of March.” New York Times. 29 Aug. 1963: 43.