How to Find Your Library's Control & Branch Numbers

For data collection purposes, the Illinois State Library issues control and branch numbers for each library. This information helps the Illinois State Library and the library systems identify library agencies and locations for membership, grants, and other purposes.  

To find your control and branch numbers, please use the directions below. 

Control number (five digits): 

  1. Start by looking for the Member Library Lookup page on the RAILS website 
  2. Type in the name of your library in the Filter Library Agency field and filter by library type (academic, public, school, or special) 
  3. Click on the agency page listed in the results; this will take you to the main agency page in L2 
  4. Look under Identifiers; your library‚Äôs control number is listed here 

Branch number (two digits): 

  1. From the main agency page in L2, scroll to the bottom to All Buildings in Agency section 
  2. Click on the link to your building location; this will take you to the location record in L2 
  3. The branch number is located under Other Information 

If you are logged in with your L2 information, the control and branch numbers are also found at the bottom of each location page (formatted like this: XXXXX_XX). This is found below the Library Certification History section.  

Note: For public schools, the branch number for the agency's primary location (i.e. the main office) is always 99. For all other library agencies, the branch number for the primary location is 00. 

If you have problems locating this information, please contact our L2 Help Desk, You can also fill out a request form on the L2 Help page