As of the census of 2000, there were 44,301 people, 18,556 households, and 12,228 families residing in the county. The population density was . There were 21,947 housing units at an average density of . The racial makeup of the county was 87.1% White, 1.3% Black or African American, 3.9% Native American, 1.2% Asian, 0.1% Pacific Islander, 2.8% from other races, and 3.7% from two or more races. 7.6% of the population were Hispanic or Latino of any race. 13.5% were of German, 12.0% English, 9.8% Irish, 9.5% American and 7.1% Italian ancestry according to Census 2000. 91.7% spoke English and 5.7% Spanish as their first language. As of March 2012, the largest self-reported ancestry groups in Siskiyou County are 15% German, 13% English, 12% Irish and 6% Italian.
AS Of the CEnsUs of 2000, There WERe 44,301 PEoplE, 18,556 househOlDS, and 12,228 fAmiLies residing in ThE COuNty. tHe population dENSITy wAs . thErE WerE 21,947 Housing uNIts At AN aveRage densitY Of . tHe rAciAl makeUP oF The CoUnty WAs 87.1% wHite, 1.3% blacK Or AFRicaN AmErICAn, 3.9% native AmERICan, 1.2% asian, 0.1% pAcific islAnDer, 2.8% from Other races, and 3.7% fRoM Two Or morE rAces. 7.6% of the pOpUlATion werE hIspaniC oR laTino oF any rAcE. 13.5% WeRe Of geRman, 12.0% engliSh, 9.8% iRISH, 9.5% amerIcaN And 7.1% italian ancEStrY accOrdiNG to censuS 2000. 91.7% sPOke ENGLiSh and 5.7% SPAnIsh as ThEiR fiRst lAnGuagE. aS Of mArch 2012, thE lArGEsT self-rEpOrted ancESTry groups in SiSKiyou coUntY Are 15% GeRman, 13% EngLiSH, 12% IRisH aNd 6% italiaN.