Harold Nelsen
I checked my census index for your Thomas in Pennsylvania and found the following: (by the way the Fitzsimmons is spelled a number of ways) as you will see them spelled: Thomas

1790 Fitzsimmons/ Northumberland Co/pg 187
1790 Fitzimons Esq/Philadelphia Co/Philadelphia City, pg 240
1790 Fitzsimmons/Philadelphia Co/ Philadelphia City, pg 245
1800 Fitzimons/Philadelphia Co/ pg 227
1810 Fitzsimons/Philadelphia Co/ North Ward/ pg 062
1820 Fitzsimmons/(widow) Lebanon Co/Heidleburg twp pg 157
1820 Fitsimmons/Philadelphia Co/Bristol twp pg 024
1830 none found

1840:
Thomas Fitzimons in Luzerne Co- Susquehanna Twp p182
Thomas Fitzsimmins in Philadelphia - N. Liberties 7th ward p192
Thomas Fitzsimmons in Jefferson Co- Rose Twp p152
Thomas Fitzsimons in Allegheny - Pittsburg S Ward p365

1850 Fitzsimmons/Montgomery Co/Upper Medion twp 397
1850 Fitzsimmons/Lancaster Co/Safeharbour/Conestoga pg 267
1850 Fitzsimmons/Wayne Co/Mount Pleasant twp pg 029
1850 Fitzimmon/Schuykill Co/New Castle twp 167

My Fitzsimmons family members left Pennsylvania mid 1840's for Iowa and Kansas mostly in Wapello and Mahaska counties in Iowa and Jefferson County in Kansas

My McGuire - John McGuire married Mary Jane Fitzsimmons in Walla Walla , WA he left Iowa mid 1860 (a widower) with 5 children for Washington State. He married Mary Jane there. I don't have much data on the McGuire surname.

Fitzsimmons Family Name Homepage
Lisa's Genealogy Pages