Barbara,

In regards to finding a town named Posada Prersolie - 
Looking at nat papers & manifests for Nechowitz who settled in Illinois I see that the town was in Suwalki district.  A search at The JewishGen Gazetteer finds this possibility:

Przerośl [Pol], Psherosl' [Rus], Psherosla [Yid], Preraslia, Przerośl Osada

Region: Suwalki

Przerośl, Poland: 54°15' N, 22°39' E

Good luck in your search,

Sherri Bobish

Searching:
RATOWSKY / CHAIMSON (Ariogala, Lith.); LEFFENFELD / FINK / KALTER (Daliowa & Jasliska, Pol.)
BOJDA / BLEIWEISS (Tarnow & Tarnobrzeg, Pol.); WALTZMAN / WALZMAN (Ustrzyki Dolne, Pol.)
LEVY (Tyrawa Woloska, Pol.); SOLON / SOLAN / SOKOLSKY (Grodek, Bialystok, Pol.)
BOBISH / BLUMENKRANZ / APPEL / WEINER / ROSENBERG (Vysoko-Litovsk, Brest, Biala Podlaska)