I did get to work some today on the John M. McJunkin you were interested in in Madison County, Texas
1850 Census - No McJunkins in Texas 1860 Census - A. E. McJankins - Wharton County p. 251 No Macjunkins 1870 Census - Andrew C. McJunkinFort Bend County p. 608 Max McJunkinFreestone County p. 52
1880 census Grimes County, Texas ED 60, p. 47 S. W. McJunkin26 White b. SCparents b. S.C. Jessie wife17white b. TX father b. NC mother b. Texas
Madisonville, Madison Co., Tx p. 308B 1880 Census ED 98, p 308 - John M. McJunkin 30 White b. GA parents b. SC Mary wife20 W b. Tx parents b. GA Bertha dau1 W b. TX Mackey Windsor 10 W nephew b. Tx parents b. GA Anderson Chesher18 W b. MSlabor [Mackey Windsor would have been a nephew to John M. McJunkin- census is relationship to head of house.]
A check of the tax records for Madison County, Tx shows that John M. McJunkin was first taxed in 1875 - which means he arrived in 1874. The 1877 tax list shows that he bought land between 1876-1877.He had 100 acres - with John Woodruff as the original owner.
Because John M. was born in 1850 it is very unlikely that he ever owned any slaves - he wasn't old enough.He was only 15 when the Civil War ended.
You had asked in the e mail to me about the Ferguson and McBride families in connection with the McJunkins from 1860-1865.Since there were no McJunkins here in Texas at that time I don't know that the connection goes back that far.
I did locate 1880 Census Madisonville, Madison Co., TX p. 306B Molly Fergusonsister white 17 b. MO living with Alice Mitchellhead 25 white b. Mo Lula Mitchelldau5 white b. TX William Mitchellson3 white b. TX
p. 308A had: James Ferguson63 black b. AL Janewife54 blackb. VA Eliza dau9 black b. TX