Other
Railroads
Canals
9
Design and construction
7
Surveying
6
Railroads and state
4
Transportation
3
Commerce
2
Costs
2
Early works to 1850
2
Locomotives
2
Anthracite coal
1
Banks and banking
1
Cars
1
Coal
1
Coal mines and mining
1
Coal trade
1
Freight
1
Hist
1
History
1
Internal improvements
1
Pennsylvania railroad
1
Plagiarism
1
Public works
1
Rates
1
Stock companies
1
Stock ownership
1
Sunbury and Erie Railroad
1
Tioga railroad
1