Question: The Diocese of Syracuse is headquartered in what county?

Context paragraphs:
List of churches in the Diocese of London: The Anglican Diocese of London forms part of the Province of Canterbury in England.  Historically the diocese covered a large area north of the River Thames, and bordered the dioceses of Norwich and Lincoln to the north and west.  The present diocese covers 177 square miles (458 km²), and 17 London boroughs, covering most of Greater London north of the Thames and west of the River Lea.  This area covers nearly all of the historic county of Middlesex, and includes the City of London in which lies its cathedral, St Paul's as well as encompassing Spelthorne, formerly in Middlesex but presently part of Surrey.  Essex formed part of the Diocese until 1846 when it became part of the Diocese of Chelmsford.  The diocese is divided into five episcopal areas each of which (except the central one) is the particular responsibility of one of the diocese's suffragan bishops.  It is further divided into archdeaconries and rural deaneries, as shown below.

Christian Brothers Academy (DeWitt, New York): Christian Brothers Academy (CBA) is a private, Catholic college preparatory school in suburban Syracuse, New York run by the Brothers of the Christian Schools, founded by St. John Baptist de La Salle.  Located within the Roman Catholic Diocese of Syracuse, the school has roughly 750 students in grades seven through twelve.  It was founded in 1900 by the Christian Brothers, who still run the school, though most of the teachers are laity.  In 1960, it moved from its original site on Willow Street in Downtown Syracuse to its current location in suburban Dewitt on Randall Road.  CBA was a boys only school until September 1987.  CBA opened its doors to girls after Syracuse's all-girls school The Franciscan Academy closed and many of those parents actively lobbied to have CBA accept female students.

Horatio Nelson White: Horatio Nelson White (February 8, 1814 – 1892) was an American architect based out of Syracuse, New York and became one of New York State's most prominent architects from about 1865 to 1880.  White designed many homes, armories, churches, and public buildings throughout Syracuse in Central New York, including the Hall of Languages at Syracuse University, the Oswego County Court House, Syracuse High School, the Weiting Block in Syracuse, Oswego's City Hall, and more.

Episcopal Diocese of Ohio: The Episcopal Diocese of Ohio is a diocese of the Episcopal Church in the United States of America comprising the northern 48 counties of the state of Ohio.  Established in 1818, it was the first diocese of the Episcopal Church to be established outside the original 13 colonies and presently consists of 95 parishes, with a membership of almost 19,000 individuals.  The diocese was contiguous with the state of Ohio, but was split into two dioceses in 1875, largely over liturgical and theological differences: The Episcopal Diocese of Ohio, which retained the original name, and the Diocese of Southern Ohio headquartered in Cincinnati.  It is one of 15 dioceses that make up the Province of the Midwest (Province 5).

Episcopal Church in Minnesota: The Episcopal Church in Minnesota, also known as the Episcopal Diocese of Minnesota, is a diocese of the Episcopal Church in the United States of America which has jurisdiction over all of Minnesota, except Clay County, which is in the Episcopal Diocese of North Dakota.  It is in Province VI and its offices are in Minneapolis.  It has two cathedrals: the Cathedral of Our Merciful Saviour in Faribault and St. Mark's Episcopal Cathedral in Minneapolis.  As of December 2013, there were 20,964 members.  It has 110 faith communities (this includes 105 churches and the organizations Episcopal Homes of Minnesota, the Episcopal House of Prayer, The Sheltering Arms Foundation, Breck School, and Shattuck-St.  Mary’s School).  It affiliated with the Minnesota Council of Churches, The Joint Religious Legislative Coalition, and The Resource Center for Churches.  Henry Benjamin Whipple was the first bishop of the Episcopal Church in Minnesota.  Brian Prior is the current bishop.  The Diocese of Duluth was established as a Missionary Diocese from the Diocese of Minnesota in 1895 and was merged back into the Diocese of Minnesota on May 24, 1955.

Roman Catholic Diocese of Syracuse: The Diocese of Syracuse is a Catholic diocese headquartered in Syracuse, New York, United States.  The current bishop is the Most Rev. Robert J. Cunningham.  The Roman Catholic Diocese of Syracuse includes 237,546 Catholics residing in seven counties of Central and South Central New York State.  The seven counties are Broome, Chenango, Cortland, Madison, Oneida, Onondaga and Oswego.

Episcopal Diocese of Tennessee: The Episcopal Diocese of Tennessee is the diocese of the Episcopal Church in the United States of America that covers roughly Middle Tennessee.  A single diocese spanned the entire state until 1982, when the Episcopal Diocese of West Tennessee was created; the Diocese of Tennessee was again split in 1985 when the Episcopal Diocese of East Tennessee was formed.  It is headquartered in Nashville, Tennessee.

Jennifer Baskerville-Burrows: Jennifer Lynn Baskerville-Burrows is an American Anglican bishop in the Episcopal Church.  In October 2016, she was elected bishop of the Episcopal Diocese of Indianapolis, and she was consecrated on April 29, 2017.  She is the first African-American woman to be elected a diocesan bishop.  Prior to her consecration, she served as Director of Networking in the Diocese of Chicago.  Previously, she was a priest in the Episcopal Diocese of Central New York, the Episcopal Diocese of Newark, and the Episcopal Diocese of California.  In addition to her parish ministry, she has been Director of Alumni and Church Relations at Church Divinity School of the Pacific and a chaplain to Syracuse University.

Roman Catholic Diocese of Buffalo: The Diocese of Buffalo is a Roman Catholic diocese headquartered in Buffalo, New York, United States.  It is included in the province of the Roman Catholic Archdiocese of New York, in the Roman Rite.  The Buffalo Diocese includes eight counties in Western New York State.  The Catholic population is nearly 700,000.  The Diocese is divided into more than 150 parishes, which also include churches, schools, convents, seminaries, hospitals, and colleges.  The Buffalo Diocese was established in 1847.  From the Buffalo Diocese, the Roman Catholic Diocese of Rochester was created in 1868.  The Most Reverend Richard Joseph Malone became the 14th bishop of the Buffalo Diocese, August 10, 2012.

Syracuse, New York: Syracuse ( ) is a city in, and the county seat of, Onondaga County, New York, in the United States.  It is the largest U.S. city with the name "Syracuse", and is the fifth most populous city in the state of New York following New York City, Buffalo, Rochester, and Yonkers.  At the 2010 census, the city population was 145,252, and its metropolitan area had a population of 662,577.  It is the economic and educational hub of Central New York, a region with over a million inhabitants.  Syracuse is also well-provided with convention sites, with a downtown convention complex.  Syracuse was named after the original Greek city Syracuse (Siracusa in Italian), a city on the eastern coast of the Italian island of Sicily.

Supporting paragraphs: Roman Catholic Diocese of Syracuse Syracuse, New York
Answer: Onondaga County