1970s Feasibility studies and early work on laser interferometer GW detectors
1979 NSF funds Caltech and MIT for the laser interferometer research and development
1989 Construction proposal for LIGO submitted to National Science Foundation
1990 National Science Board approves LIGO construction proposal
1991 LIGO project receives 19 site proposals from 17 states
1992 NSF selects LIGO sites in Hanford, WA, and Livingston, LA
LIGO Cooperative Agreement signed by NSF and Caltech
1993 NSF review panel endorses technical status of LIGO
1994 Groundbreaking at Hanford site
Site construction activities underway at Hanford and Livingston locations
1996 Installation of vacuum beam tubes begins at Hanford
1997 LIGO prototype demonstrates "splitting a fringe" at LIGO sensitivty goal
Buildings at Hanford accepted and occupied
1998 40-Meter interferometer operated with LIGO optical configuration
First completed mirrors arrive at LIGO
1999 First module at Livingston completes bake
LIGO inauguration ceremony
2000 Completed installation of interferometer components for Hanford two-kilometer interferometer
Completed the bake of beam tube(s) at Livingston
Achieved 'first lock' on Hanford 2-km interferometer in recombined configuration with both Fabry-Perot arms
2001 Achieved 'first lock' on Hanford 2-km interferometer in power-recycled configuration
E7 Engineering run, first coincident operation of all interferometers plus GEO600 interferometer in Germany and LSU bar detector
2002 First data-collection Observation (S1) employing all three LIGO interferometers in conjunction with the GEO600 and TAMA300 (Japan) interferometers
2003 Second Observation (S2) operating with TAMA300 interferometer
Third Observation (S3) operating with GEO600 and TAMA300 interferometers
2004 Installation of active anti-seismic system at LLO
Hanford interferometers approach design sensitivity
2005 LIGO design sensitivity achieved
Start of Observation 5 (S5) - a cumulative year long data run at design sensitivity
2006 Science Education Center inaugurated at the LIGO Livingston Observatory
2007 Agreement for joint data analysis ratified between LIGO and Virgo (Italy)
Joint observation commences with Virgo
S5 ends; one-year, two-site coincident data at design sensitivity accumulated
2008 Start of Advanced LIGO construction
2009 Start of Sixth Observation (S6) with enhanced initial LIGO instruments
2010 S6 ends; initial LIGO operations conclude; Advanced LIGO installation begins
2011 Testing of a 4-km arm at Hanford, using Advanced LIGO optics, suspensions, isolation system, and controls
Begin testing of prototype squeezed light apparatus to improve sensitivity with kilometer-scale interferometer at Hanford
Testing of the Advanced LIGO stabilized laser and input mode cleaner cavity at Livingston
2012 Advanced LIGO: first 4km cavity locked; first pre-stabilized laser mode cleaner locked
2013 Advanced LIGO: Completion of fabrication, completion of vertex interferometer testing at Livingston
2014 Acceptance of all Advanced LIGO interferometers
2015 First Observing Runs with the Advanced LIGO Interferometers