U.S. Federal Route 40 is a east-west highway across Central St. Charles County. This runs along a expressway corridor through the entire county. From the Missouri River to near Dardenne Prairie it runs with Interstate 64. Dardenne Prairie to Interstate 70 this is being up-graded to a expressway. U.S. Rt. 40 joins Interstate 70 to the St. Charles/Warren County Line. U.S. Rt. 40 passes thorugh the following towns in St. Charles County. Weldon Springs
St. Peters Dardenne Prairie
O'fallon
Lake St. Louis
Wentzville
U.S. Rt. 40 is multi-plexed in St. Charles County. Interstate 64, from the St. Louis/St. Charles County Line to near Darenne Park. U.S. Rt. 61, from the St. Louis/St. Charles County Line to Wentzville.
Interstate 70, from Wentzville to the St. Charles/Warren County Line.
WB I-64/U.S. Rt. 40; NB U.S. Rt. 61 at the St. Louis/St. Charles County Line. EB I-64/U.S. Rt. 40; SB U.S. Rt. 61 crossing the Missouri River. EB I-64/U.S. Rt. 40; SB U.S. Rt. 61 at the Missouri River. WB I-64/U.S. Rt. 40; NB U.S. Rt. 61 west of the Boone Bridge. EB I-64/U.S. Rt. 40; SB U.S. Rt. 61 east of Research Park Circle. WB I-64/U.S. Rt. 40; NB U.S. Rt. 61 at Research Park Circle. WB I-64/U.S. Rt. 40; NB U.S. Rt. 61 east of MO St Rt 94. EB I-64/U.S. Rt. 40; SB U.S. Rt. 61 east of MO St Rt 94. A junction marker on WB MO St Rt 94. A BGS on WB MO St Rt 94. WB I-64/U.S. Rt. 40; NB U.S. Rt. 61 in Weldon Springs. WB I-64/U.S. Rt. 40; NB U.S. Rt. 61 at Town Square Road. WB I-64/U.S. Rt. 40; NB U.S. Rt. 61 at MO Sec St Rt DD. EB I-64/U.S. Rt. 40; SB U.S. Rt. 61 south of MO St Rt 364/MO Sec St Rt N. WB I-64/U.S. Rt. 40; NB U.S. Rt. 61 at MO St Rt 364/MO Sec St Rt N. WB I-64/U.S. Rt. 40; NB U.S. Rt. 61 near MO Sec St Rt N. EB I-64/U.S. Rt. 40; SB U.S. Rt. 61 at MO St Rt 364/MO Sec St Rt N. A BGS on WB MO St Rt 364. A BGS on WB MO St Rt 364. A BGS on WB MO St Rt 364. A BGS on WB MO St Rt 364. A BGS on EB MO St Rt 364. A BGS on EB MO St Rt 364. A junction marker on EB MO Sec St Rt N. EB I-64/U.S. Rt. 40; SB U.S. Rt. 61 west of MO St Rt 364/MO St Rt N. WB I-64/U.S. Rt. 40; NB U.S. Rt. 61 west of MO St Rt 364/MO Sec St Rt N. WB I-64/U.S. Rt. 40; NB U.S. Rt. 61 near Lake St. Louis. WB U.S. Rt. 40; NB U.S. Rt. 61 near Lake St. Louis. WB U.S. Rt. 40; NB U.S. Rt. 61 in Lake St. Louis. Several interchanges have been built along U.S. Rt. 40/61, but the expressway has not been complete. Thus the roadway shifts several times. (July, 2004) Same point as the picture above. (July, 2009) WB U.S. Rt. 40/NB U.S. Rt. 61 near Prospect Road. WB I-64/U.S. Rt. 40; NB U.S. Rt. 61 near Prospect Road. WB I-64/U.S. Rt. 40; NB U.S. Rt. 61 at Prospect Road. EB I-64/U.S. Rt. 40; SB U.S. Rt. 61 east of Prospect Road. WB U.S. Rt. 40/NB U.S. Rt. 61 at one of the last overpasses being built. (July, 2009) WB I-64/U.S. Rt. 40; NB U.S. Rt. 61 one mile from I-70. (September, 2010) WB U.S. Rt. 40/NB U.S. Rt. 61 south of I-70. WB U.S. Rt. 40/NB U.S. Rt. 61 at EB I-70. (July, 2004) The same point as the photo above. (July, 2009) WB I-64/U.S. Rt. 40; NB U.S. Rt. 61 at EB I-70. (June, 2019) WB I-64/U.S. Rt. 40; NB U.S. Rt. 61 at WB I-70. (June, 2019) A BGS on WB I-70. A BGS on WB I-70. EB I-70/U.S. Rt. 40 at I-64/U.S. Rt. 61. EB I-70/U.S. Rt. 40 west of I-64/U.S. Rt. 40. A BGS on EB I-70/U.S. Rt. 40. EB I-70/US. Rt. 40 in Wentzville. EB I-70/U.S. Rt. 40 in Wentzville. A junction marker on SB MO Sec St Rt Z. A BGS on SB MO Sec St Rt Z. A BGS on EB I-70/U.S. Rt. 40. A set of guide BGS's in Wentzville. A BGS on Wentzville Parkway. WB I-70/U.S. Rt. 40 at David Hokel Parkway. A BGS on SB MO Sec St Rt W. A set of guide markers on NB MO Sec St Rt W. A set of guide markers on NB MO Sec St Rt T.
