There he worked for a while for a government body in Washington D.C., where he published on the economics of transportation focusing on optimal routing, then moved to Chicago where he joined a research body Cowles Commission for Research in Economics affiliated with the University of Chicago.
Di sana ia bekerja untuk badan pemerintahan di Washington D.C., di mana ia menerbitkan karya tentang ekonomi transportasi berfokus pada pengarahan optimal, lalu pindah ke Chicago di mana ia bergabung dengan sebuah badan riset yang berafiliasi dengan Universitas Chicago.