| 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 | December | Construction proposal for LIGO submitted to National Science Foundation |
| 1990 | May | National Science Board approves LIGO construction proposal |
| 1991 | March | LIGO project receives 19 site proposals from 17 states |
| 1992 | February | NSF selects LIGO sites in Hanford, WA, and Livingston, LA |
| May | LIGO Cooperative Agreement signed by NSF and Caltech | |
| 1993 | Summer | NSF review panel endorses technical status of LIGO |
| 1994 | July | Groundbreaking at Hanford site |
| Winter | Site construction activities underway at Livingston location | |
| 1996 | October | Installation of vacuum beam tubes begins at Hanford |
| 1997 | June | First polished glass received by LIGO |
| July | LIGO prototype demonstrates "splitting a fringe" at LIGO sensitivty goal | |
| August | Buildings at Hanford accepted and occupied | |
| December | LIGO receives final shipment of raw glass | |
| 1998 | May | First completed mirrors arrive at LIGO |
| September | 40-Meter interferometer operated with LIGO optical configuration | |
| December | First completed mirrors arrive at LIGO | |
| 1999 | April | Polishing of mirrors |
| June | Coating of mirrors complete | |
| September | First module at Livingston completes bake | |
| November | LIGO inauguration ceremony | |
| 2000 | May | Completed installation of interferometer components for Hanford two-kilometer interferometer |
| June | Completed the bake of beam tube(s) at Livingston | |
| October | Achieved 'first lock' on Hanford 2-km interferometer in recombined configuration with both Fabry-Perot arms | |
| 2001 | January | Achieved 'first lock' on Hanford 2-km interferometer in power-recycled configuration |
| December | E7 Engineering run, first coincident operation of all interferometers plus GEO600 interferometer in Germany and LSU bar detector | |
| 2002 | August | First data-collection Science Run (S1) emplying all three LIGO interferometers in conjunction with the GEO600 and TAMA300 (Japan) interferometers |
| 2003 | Feb-Apr | Second Science Run (S2) operating with TAMA300 interferometer |
| Spring | Further commissioning yields still greater sensitivity gains | |
| Nov-Dec | Third Science Run (S3) operating with GEO600 and TAMA300 interferometers | |
| 2004 | Spring | Seismic interference difficulties at Livingston overcome with installation of active anti-seismic system |
| Fall | Hanford interferometers approach design sensitivity | |
| 2005 | Feb-Mar | Fourth Science Run (S4) performed |
| March | LIGO design sensitivity achieved | |
| Fall | Demonstration of Advanced LIGO laser power | |
| November | Start of Science Run 5 (S5) - a cumulative year long data run at design sensiivity | |
| 2006 | Jan-Dec | S5 continues, new standards reached in interferometer performance and duty factors |
| November | Science Education Center inaugurated at the LIGO Livingston Observatory | |
| 2007 | January | Agreement for joint data analysis ratified between LIGO and Virgo (Italy) |
| May | Joint science-observation running commences with Virgo | |
| October | S5 ends; one-year, two-site coincident data at design sensitivity accumulated | |
| 2008 | May | Start of Advanced LIGO construction |
| 2009 | July | Start of Sixth Science Run (S6) with enhanced initial LIGO instruments |
| 2010 | October | S6 ends; initial LIGO operations conclude; Advanced LIGO installation begins |
| 2011 | Summer |
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 |
| Fall | Testing of the Advanced LIGO stabilized laser and input mode cleaner cavity at Livingston | |
| 2012 | Winter | Wrap up of squeezed light test at Hanford; start installation of the Hanford 4-km Advanced LIGO interferometer |
| Spring | At Livingston, test all Advanced LIGO optics and controls in the central building, performing interferometry on an approximate 10-meter baseline | |
| Summer | At Hanford, test all Advanced LIGO optics and controls in the central building, performing interferometry on an approximate 10-meter baseline | |
| Fall | At Livingston, complete Advanced LIGO installation; start testing complete interferometer | |
| 2013 | Winter | Hanford 2-km Advanced LIGO interferometer installation complete; begin testing Hanford 2-km interferometer |
| Summer |
Accept Livingston Advanced LIGO interferometer Hanford 4-km Advanced LIGO interferometer installation complete; begin testing Hanford 4-km interferometer | |
| Fall | Accept Hanford Advanced LIGO 2-km interferometer | |
| 2014 |
Accept Hanford Advanced LIGO 4-km interferometer All Advanced LIGO interferometers operational; Advanced LIGO observations begin | |