Moore was born in Lafayette County, Mississippi. Moore graduated from the University of Arkansas in 1881. He studied law and was admitted to the Arkansas bar in 1882. From 1894 to 1900, Moore served as probate judge in Phillips County, Arkansas. He was elected to the Arkansas House of Representatives in 1882, 1901, and 1903. In 1903, he served as Speaker of the House.
In 1904 Moore was elected to the Arkansas Senate. He served terms in the Senate in 1905, 1907, 1913, and 1915.
On 11 February 1907, Governor John Sebastian Little resigned from office due to mental and physical illness, and John Isaac Moore, who was president of the Senate at the time, became acting governor. He served as governor until the legislature adjourned on 14 May 1907. Moore was later a member of the Arkansas Constitutional Convention.
Category:Arkansas State Senators
Category:Governors of Arkansas
Category:Members of the Arkansas House of Representatives
Category:People from Phillips County, Arkansas
Category:People from Lafayette County, Mississippi
Category:Place of death missing
Category:University of Arkansas alumni
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