1840 Census - Greene County, Pennsylvania
Monongahela TWP

  Nancy Hartly
  1 Female under 5
  1 Female 5-10
  1 Female 15-20
  1 Female 30-40

  Mary Hartly
  1 Female 10-15
  1 Female 70-80

1850 Census - Fayette Co., PA Nicholson TWP

  61 61
  Theoren Provence   28 M Farmer 1500 PA
  Maria              25 F             PA
  Elvira              7 F             PA
  Joseph N.           5 M             PA
  James C.            3 M             PA
  Nancy            9/12 F             PA
  Lydia Hartley      12 F             PA

  73 73
  John Ache          38 M Farmer 7000 PA
  Martha             31 F             PA
  Jefferson          11 M             PA
  Louisa              9 F             PA
  Hannah              6 F             PA
  Mary J. Hartley    21 F             PA
  James              20 M Laborer     PA
  Jefferson Ferren   17 M Do          PA
  [I think Martha is related to Maria because they took in some of the Hartley children]

1860 Census - Fayette Co.,PA Nicholson TWP

  208 208
  Theren Provance  40 M Farmer 2000 350 PA
  Ann              36 F                 PA
  Elvira           17 F                 PA
  Joseph           15 M                 PA
  James            13 M                 PA
  Nancy            11 F                 PA
  Benjamin          9 M                 PA
  Lewis             7 M                 PA
  Theren            5 M                 PA
  Rachel            3 F                 PA

  209 209
  Reuben Parschall 34 M  Farmer      PA
  Mary Hartly      30 F  Housekeeper PA

  220 220
  Martha Ache      45 F Farmer   7000 500 Pa
  Jefferson        21 M do                Pa
  Louisa           18 F                   Pa
  Hannah           17 F                   Pa
  Mary             75 F                   Va

  224 224
  Nancy Hartley   59 F            PA
  James Hartley   26 M    Cropper PA
  Eliza           25 F            PA

1870 Census - Fayette Co., PA Nicholson TWP

  182 191
  Provins, H.M.   46 F Keeping House  PA
  J.H.            23 M                PA
  J.M.            22 M                PA
  N.C.            20 F                PA
  Ben F.          18 M                PA
  Lewis           16 M                PA
  Theren          14 M                PA
  Rachel          11 F                PA
  Hartly, Nancy   64 F                PA

Ancestry.com did not index Monongahela TWP, Greene County, Pennsylvania for the 1870 census.  I was
able to manually find the following Hartly families there in 1870:

1870 Census - Greene County, Pennsylvania
Monongahela TWP - 8 June 1870

  96 96
  Hartly, Josephus   61 M W Farmer 8150 2730 Pa
  Sarah              58 F W Keeping House    Pa
  Rebecca E.         19 F W At Home          Pa
  Oscar              16 M W At Home          Pa
  Thompson, Rebecca  36 F W Domestic Servant Pa

  97 97
  Hartly, Samuel     63 M W Farmer 14000 1925 Pa
  Elizabeth          57 F W Keeping House     Pa
  Harriet            22 F W At Home           Pa
  Stephen            24 M W Labors on Farm    Pa
  Mary               26 F W At Home           Pa
  Josephine          20 F W At Home           Pa
  Rebecca            18 F W At Home           Pa
  Amanda             16 F W At Home           Pa
  Worthington, Vincent 31 M W Labors on Farm   Pa
  ---, Hanna         30 F W At Home           Pa
  Hyde, Hiram        40 M W                   Pa
  Wells, William     11 M W Labors on Farm    Pa
  Thompson, Minor     8 M W                   Pa