Question: What forms the western boundary of the county that WAID is licensed to?

full_context: Document 1: WABE: WABE FM 90.1 is a radio station in Atlanta, Georgia, that is affiliated with National Public Radio (NPR) and Public Radio International (PRI). WABE's format features mostly classical music, although the station will occasionally play a Beatles tune, a Broadway show tune, a film suite, or a selection from a film such as "Star Wars", as long as the piece is in a classical-sounding arrangement. WABE-FM has lately added the short feature "Atlanta Sounds" (broadcast several times a day) and twice weekly previews of weekend events around the city. Beginning in 2009, its Sunday schedule changed from devoting equal time to news programs and classical music to broadcasting news programs during the daytime and playing classical music on Sunday evenings. It carries the NPR flagship programs "Morning Edition" and "All Things Considered", with newscasts interjected periodically.
Document 2: WBTP: WBTP is an urban contemporary radio station that serves the Tampa Bay area that plays hip-hop, R&B, and soul music that aims towards the African American community. It is owned and operated by iHeartMedia. Its target audience is African Americans between the ages of 18-34, but its main competitor is WLLD, which has a very similar target audience as well. It was the home of former Russ Parr Morning Show co-host, Olivia Fox, who was host of the station's morning drive show from 2004 to mid-2006. Licensed to Clearwater, the station's studios are located in South Tampa and the transmitter site is in Gandy.
Document 3: Choctaw County, Mississippi: Choctaw County is a county located in the central part of U.S. state of Mississippi. As of the 2010 census, the population was 8,547. Its northern border is the Big Black River, which flows southwest into the Mississippi south of Vicksburg. The county seat is Ackerman. The county is named after the Choctaw tribe of Native Americans, who long occupied this territory as their homeland before being forced to move west of the Mississippi River by federal troops under the Indian Removal Act of 1830.
Document 4: Mississippi Delta: The Mississippi Delta is the distinctive northwest section of the U.S. state of Mississippi which lies between the Mississippi and Yazoo Rivers. The region has been called "The Most Southern Place on Earth" ("Southern" in the sense of "characteristic of its region, the American South"), because of its unique racial, cultural, and economic history. It is 200 miles long and 87 miles across at its widest point, encompassing circa 4,415,000 acres, or, some 7,000 square miles of alluvial floodplain. Originally covered in hardwood forest across the bottomlands, it was developed as one of the richest cotton-growing areas in the nation before the American Civil War (1861-1865). The region attracted many speculators who developed land along the riverfronts for cotton plantations; they became wealthy planters dependent on the labor of black slaves, who comprised the vast majority of the population in these counties well before the Civil War, often twice the number of whites.
Document 5: WAJM: WAJM, assigned to 88.9 FM and licensed to Atlantic City, New Jersey, is a high school radio station owned by the Atlantic City Board of Education and is operated by the students of Atlantic City High School. Currently, WAJM broadcasts live Monday thru Friday from 7:00am to 3:30pm and during after hours, on weekends, holidays and when Atlantic City High School is closed due to inclement weather the station operates on an automated system where music, station IDs and PSA are shuffled and broadcast on-air. Starting at its inception WAJM had been broadcasting with a jazz radio format until 2009 when it flipped to a freeform radio format using the moniker 88.9 The Jam. The studios, offices and transmitter are located on the campus of Atlantic City High School on North Albany Avenue in Atlantic City. In 2009 WAJM began simulcasting its live and automated broadcasts via the Internet in both an audio only feed and audio/video feed. The station was a creation of Mr.Norman Draper. The first school year of on air broadcasting was 1996-97. That year the students interviewed "Sugar" Ray Leonard, and did a live simulcast from the grand opening of the new Atlantic City Convention Center.
Document 6: WOL (AM): WOL is an urban talk radio station in Washington, D.C. Broadcasting on 1450 AM, this is the flagship radio station of Radio One. It is co-owned with WKYS, WMMJ, WPRS and WYCB and has studios located in Silver Spring, Maryland. The transmitter site is in Fort Totten in Washington.
Document 7: WRBJ-FM: WRBJ-FM (97.7 FM) is an urban contemporary radio station in Jackson, Mississippi, but licensed to Brandon, Mississippi. The station is owned and operated by Roberts Broadcasting, former owners of The CW television affiliate WRBJ. Its studios are located at The Roberts Building along State Street in Jackson, just two blocks north of the Mississippi State Capitol building, and the transmitter tower is south of Brandon.
Document 8: WAID: WAID (106.5 FM) is a radio station broadcasting an Urban Contemporary format. Licensed to Clarksdale, Mississippi, USA, the station, also known as "Power 106.5," is currently owned by Radio Cleveland and features programming from ABC Radio . The station broadcasts the nationally syndicated Tom Joyner Morning Show and Doug Banks show.
Document 9: WDJR: WDJR (96.9 FM, "The Legend") is an American Classic Country formatted radio station based in Dothan, Alabama. The station is owned and operated by Gulf South Communications. The station's signal, which originates from a transmitter in Holmes County Florida, reaches large portions of Alabama, Florida, and Georgia.
Document 10: Clay County, Mississippi: Clay County is a county located in the U.S. state of Mississippi. As of the 2010 census, the population was 20,634. Its county seat is West Point. Its name is in honor of American statesman Henry Clay, member of the United States Senate from Kentucky and United States Secretary of State in the 19th century.
Document 11: West Point, Mississippi: West Point is a city in Clay County, Mississippi, in the Golden Triangle region of the state. The population was 11,307 at the 2010 census. It is the county seat of Clay County and the principal city of the West Point Micropolitan Statistical Area, which is part of the larger Columbus-West Point Combined Statistical Area.
Document 12: Clarksdale, Mississippi: Clarksdale is a city in Coahoma County, Mississippi, and seat of the county. The western boundary of the county is formed by the Mississippi River. Located in the Mississippi Delta region, Clarksdale is an agricultural and trading center. It has been home to many blues musicians. Clarksdale is named after John Clark, who founded the city in the mid-19th century.
Document 13: WAPT: WAPT is an ABC-affiliated television station licensed to Jackson, Mississippi, United States. Owned by the Hearst Television subsidiary of the Hearst Corporation, it broadcasts a high definition digital signal on UHF channel 21 (or virtual channel 16 via PSIP) from a transmitter at its studios on Channel 16 Way in southwest Jackson. On cable, the station can be seen on Comcast Xfinity channel 4, Cable One channel 16 and Vicksburg Video channel 9. There is a high definition feed provided on Xfinity digital channel 431, Cable One digital channel 1016 and Vicksburg Video digital channel 225.
Document 14: Mississippi's 2nd congressional district: Mississippi's 2nd congressional district (MS-2) is the only majority-black district in the state, covering much of western Mississippi. The district includes most of Jackson, the riverfront cities of Greenville and Vicksburg, and the interior market cities of Clarksdale, Greenwood, and Clinton. The district is approximately 275 mi long, 180 mi wide and borders the Mississippi River; it encompasses much of the Mississippi Delta, and a total of 15 counties and parts of several others.
Document 15: Dockery Plantation: Dockery Plantation was a 25600 acre cotton plantation and sawmill in Dockery, Mississippi, on the Sunflower River between Ruleville and Cleveland, Mississippi. It is widely regarded as the place where Delta blues music was born. Blues musicians resident at Dockery included Charlie Patton, Robert Johnson and Howlin' Wolf. The property was added to the National Register of Historic Places in 2006.
ground_truth: the Mississippi River