The rule of thumb is to use the information found closest to the date of the event. Of course the immigration records would be the best source. Sometimes obituaries say where the person was born but that info was probably supplied by the wife or children.
In 1900 the Ranko family was living in Roslyn, Kittitas Co., WA.
John Ranko, b. Austria (and both sets of parents) Oct 1865, immigrated 1878, naturalized, marr 9yrs, coal miner.
Annie, wife, b. Austria, May 1875, immigrated 1887.
John, b. PA, Sept. 1891.
Annie, b. WA June 1884.
Frank, b. WA Feb 1895.
Joseph b. WA Aug 1887.
Charles, b. WA March 1900.
Steve, brother, b. Austria, 27, immigrated 1880, coal miner.
This tells me that came came to the USA on the East Coast and that's where you should look for their immigration records. Unfortunately, there were many ports of entry on the East Coast.
In 1910 John, Anna and some of the children were living in Roslyn Ward 2, Kittitas Co., WA.
John Ranko, b. Hungary, 45, speaks Slovak and same for both sets parents, immigrated 1879, naturalized, marr 20yrs, teamster coal miner.
Anna, b. Hungary, speaks Slovak, 36, imm 1897, had given birth to four children but only three alive in 1910.
Anna, b. WA, 17.
George, b. WA, 6.
William, b. WA, 3.
Anna Ranko of Roslyn, 18 yrs old, born-WA first marriage to Sam Maybo of Roslyn, b. Austria, Occupation=miner.
Sam's father=Andy Maybo, b. Austria.
Sam's mother-Anna Kohl, b. Austria.
Anna's father=John Ranko, b. Austria.
Anna's mother=Anna Husko, b. Austria.
Married= 23 Oct 1911, Seattle, King Co., WA. Source: Washington State Digital Archives. You can view and print the document at no charge.
In 1920 John, Anna and some children were living in Ronald, Kittias Co., WA.
John Ranko, b. Austria and both sets of parents, imm 1892, nat, coal miner, 54.
Anna, wife, b. Austria, 44.
Charlie, b. WA, 20, single, coal miner.
George, b. WA, 16.
Willie, b. WA, 13.
Frank, b. WA, 31.
John Ranko died 25 Oct 1920, 54 yrs old, in Roslyn, Kittitas Co., WA.
Father's Name-=John Ranko.
Spouse=Annie Ranko. Source: Washington State Digital ARchives.
You can request a copy of John's obituary from the Washington State Library, sos.wa.gov/library/genealogy.aspx .
In 1930 Anna was living with her daughter Maria and husband Clarence in Seattle, King Co., WA.
Clarence R. Green, head household, b. SD, 32, marr @ 21, motorman street car.
Maria E., wife, b. WA, 28, marr @ 17.
Anna Ranko, malaw, b. Yogoslavia, 55, divorced.
Frank Ranko, brotherlaw, b. WA, 35, divorced stone worker stone works.
William Ranko, brotherlaw, b. WA, 23, single, stone worker too.
I didn't find Anna's death info but all of the deaths are loaded into the Washington State Digital Archives database yet.
John Ranko on June 5, 1917 was living in Tono, Thurston Co., WA.
Birth=17 Sept 1891, Nanticoke?, PA.
Occupation=Miner, Washington Union Coal Co., Tono.
Claimed exemption from World War I service because of wife and three children. Source: World War I Draft Registration Cards 1917-18.
In 1920 John, wife and children were living in Issaquah, King Co., WA.
John W. Ranko, b. PA, 28, both parents b. Austria but spoke Slovak, coal miner.
Susie, wife, b. Germany, 24, immigrated 1900, naturalized.
Irene, b. Canada, 7.
Aneta, b. WA, 4 4/12ths.
Myra, b. WA, 2 7/12ths.
Mike Skovena, father [but should say fatherlaw], b. Poland, 52, imm 1898, pending papers for citizenship, coal miner.
Well I'll stop here because any other info would be too far away from the date to be useful. I'd center my search around John's birthday 17 Sept. 1891 in Nanticoke, PA. Successful Searching!