Due to its size, favorable climate, rich fishing waters and proximity to Saint Petersburg, the capital of the Russian Empire, the Karelian Isthmus became the wealthiest part of Finland once the industrial revolution had gained momentum in the 19th century. The railroads Saint Petersburg–Vyborg–Riihimäki (1870), Vyborg–Hiitola–Sortavala (1893), Saint Petersburg–Kexholm–Hiitola (1917) crossed the isthmus, contributing to its economic development. By the end of the 19th century the nearby areas along the Saint Petersburg–Vyborg section had become popular place of summer resort for wealthy Saint Petersburgers.