Why are there two routing numbers at Bank of America?

Burling Bank 6 Citizens Savings Bank 7 First Freedom Bank 3 First National Bank at Saint James 1 First National Bank of Clarksdale 4 First National Bank of Griffin 17 Independent Correspondent Bank 13 JONESTOWN B&TC OF JONESTOWN PA 21 Northern State Bank of Virginia 8 PARAGON Bank 18 SABINE ST B&TC 12 Security Bank USA 8 Security State Bank of Marine 2 Signature Bank of Georgia 4 SSB Community Bank 14 TERRABANK National Association 7 Texana Bank, National Association 3 TPNB Bank 11 TrailWest Bank 4 TWO RIVERS B&TC 10