diff --git a/doc/src/vpr/command_line_usage.rst b/doc/src/vpr/command_line_usage.rst
index fc575e08a13..fa0cd49017b 100644
--- a/doc/src/vpr/command_line_usage.rst
+++ b/doc/src/vpr/command_line_usage.rst
@@ -1120,6 +1120,14 @@ VPR uses a negotiated congestion algorithm (based on Pathfinder) to perform rout
 
 .. seealso:: :ref:`timing_driven_router_options`
 
+.. option:: --flat_routing {on | off}
+
+    If this option is enabled, the *run-flat* router is used instead of the *two-stage* router.
+    This means that during the routing stage, all nets, both intra- and inter-cluster, are routed directly from one primitive pin to another primitive pin.
+    This increases routing time but can improve routing quality by re-arranging LUT inputs and exposing additional optimization opportunities in architectures with local intra-cluster routing that is not a full crossbar.
+
+    **Default:** ``OFF`
+
 .. option:: --max_router_iterations <int>
 
     The number of iterations of a Pathfinder-based router that will be executed before a circuit is declared unrouteable (if it hasn’t routed successfully yet) at a given channel width.
diff --git a/vpr/src/base/read_options.cpp b/vpr/src/base/read_options.cpp
index 0764b76f947..b734b82b850 100644
--- a/vpr/src/base/read_options.cpp
+++ b/vpr/src/base/read_options.cpp
@@ -31,6 +31,7 @@ t_options read_options(int argc, const char** argv) {
 
 struct ParseOnOff {
     ConvertedValue<bool> from_str(std::string str) {
+        std::transform(str.begin(), str.end(), str.begin(), ::tolower);
         ConvertedValue<bool> conv_value;
         if (str == "on")
             conv_value.set_value(true);
@@ -42,7 +43,6 @@ struct ParseOnOff {
             conv_value.set_error(msg.str());
         }
         return conv_value;
-        ;
     }
 
     ConvertedValue<std::string> to_str(bool val) {
@@ -2441,9 +2441,9 @@ argparse::ArgumentParser create_arg_parser(std::string prog_name, t_options& arg
         .default_value("1")
         .show_in(argparse::ShowIn::HELP_ONLY);
 
-    route_grp.add_argument(args.flat_routing, "--flat_routing")
+    route_grp.add_argument<bool, ParseOnOff>(args.flat_routing, "--flat_routing")
         .help("Enable VPR's flat routing (routing the nets from the source primitive to the destination primitive)")
-        .default_value("false")
+        .default_value("off")
         .show_in(argparse::ShowIn::HELP_ONLY);
 
     route_grp.add_argument(args.has_choking_spot, "--has_choking_spot")
diff --git a/vtr_flow/tasks/regression_tests/vtr_reg_nightly_test7/titan_other_run_flat/config/config.txt b/vtr_flow/tasks/regression_tests/vtr_reg_nightly_test7/titan_other_run_flat/config/config.txt
index aafaa2a7def..ee25489239f 100644
--- a/vtr_flow/tasks/regression_tests/vtr_reg_nightly_test7/titan_other_run_flat/config/config.txt
+++ b/vtr_flow/tasks/regression_tests/vtr_reg_nightly_test7/titan_other_run_flat/config/config.txt
@@ -41,5 +41,5 @@ qor_parse_file=qor_vpr_titan.txt
 # Pass requirements
 pass_requirements_file=pass_requirements_vpr_titan.txt
 
-script_params=-starting_stage vpr --route_chan_width 300 --max_router_iterations 400 --router_lookahead map --flat_routing true
+script_params=-starting_stage vpr --route_chan_width 300 --max_router_iterations 400 --router_lookahead map --flat_routing on
 
diff --git a/vtr_flow/tasks/regression_tests/vtr_reg_nightly_test7/verify_router_lookahead_run_flat/config/config.txt b/vtr_flow/tasks/regression_tests/vtr_reg_nightly_test7/verify_router_lookahead_run_flat/config/config.txt
index 67c2c9f502a..fa513365115 100644
--- a/vtr_flow/tasks/regression_tests/vtr_reg_nightly_test7/verify_router_lookahead_run_flat/config/config.txt
+++ b/vtr_flow/tasks/regression_tests/vtr_reg_nightly_test7/verify_router_lookahead_run_flat/config/config.txt
@@ -27,4 +27,4 @@ qor_parse_file=qor_rr_graph.txt
 pass_requirements_file=pass_requirements_verify_rr_graph.txt
 
 # Script parameters
-script_params = -verify_inter_cluster_router_lookahead -verify_intra_cluster_router_lookahead --route_chan_width 130 --flat_routing true
+script_params = -verify_inter_cluster_router_lookahead -verify_intra_cluster_router_lookahead --route_chan_width 130 --flat_routing on
diff --git a/vtr_flow/tasks/regression_tests/vtr_reg_nightly_test7/verify_rr_graph_run_flat/config/config.txt b/vtr_flow/tasks/regression_tests/vtr_reg_nightly_test7/verify_rr_graph_run_flat/config/config.txt
index 8200d0b72ba..9a3155eb899 100644
--- a/vtr_flow/tasks/regression_tests/vtr_reg_nightly_test7/verify_rr_graph_run_flat/config/config.txt
+++ b/vtr_flow/tasks/regression_tests/vtr_reg_nightly_test7/verify_rr_graph_run_flat/config/config.txt
@@ -27,4 +27,4 @@ qor_parse_file=qor_rr_graph.txt
 pass_requirements_file=pass_requirements_verify_rr_graph.txt
 
 # Script parameters
-script_params = -verify_rr_graph --route_chan_width 130 --flat_routing true
+script_params = -verify_rr_graph --route_chan_width 130 --flat_routing on
diff --git a/vtr_flow/tasks/regression_tests/vtr_reg_nightly_test7/vtr_reg_qor_large_depop_run_flat/config/config.txt b/vtr_flow/tasks/regression_tests/vtr_reg_nightly_test7/vtr_reg_qor_large_depop_run_flat/config/config.txt
index 01eba58da65..3cf73435272 100755
--- a/vtr_flow/tasks/regression_tests/vtr_reg_nightly_test7/vtr_reg_qor_large_depop_run_flat/config/config.txt
+++ b/vtr_flow/tasks/regression_tests/vtr_reg_nightly_test7/vtr_reg_qor_large_depop_run_flat/config/config.txt
@@ -29,4 +29,4 @@ qor_parse_file=qor_standard.txt
 pass_requirements_file=pass_requirements.txt
 
 #Script parameters
-script_params=-track_memory_usage --max_router_iterations 300 --flat_routing true --has_choking_spot true
+script_params=-track_memory_usage --max_router_iterations 300 --flat_routing on --has_choking_spot true
diff --git a/vtr_flow/tasks/regression_tests/vtr_reg_nightly_test7/vtr_reg_qor_large_run_flat/config/config.txt b/vtr_flow/tasks/regression_tests/vtr_reg_nightly_test7/vtr_reg_qor_large_run_flat/config/config.txt
index be28691892d..43482b7e4a9 100755
--- a/vtr_flow/tasks/regression_tests/vtr_reg_nightly_test7/vtr_reg_qor_large_run_flat/config/config.txt
+++ b/vtr_flow/tasks/regression_tests/vtr_reg_nightly_test7/vtr_reg_qor_large_run_flat/config/config.txt
@@ -31,4 +31,4 @@ qor_parse_file=qor_large.txt
 pass_requirements_file=pass_requirements.txt
 
 #Script parameters
-script_params=-track_memory_usage -max_router_iterations 300 --flat_routing true
+script_params=-track_memory_usage -max_router_iterations 300 --flat_routing on
diff --git a/vtr_flow/tasks/regression_tests/vtr_reg_strong/strong_flat_router/config/config.txt b/vtr_flow/tasks/regression_tests/vtr_reg_strong/strong_flat_router/config/config.txt
index 4e4071f98c2..d59d17d4831 100644
--- a/vtr_flow/tasks/regression_tests/vtr_reg_strong/strong_flat_router/config/config.txt
+++ b/vtr_flow/tasks/regression_tests/vtr_reg_strong/strong_flat_router/config/config.txt
@@ -24,6 +24,6 @@ qor_parse_file=qor_standard.txt
 # Pass requirements
 pass_requirements_file=pass_requirements.txt
 
-script_params_common=-track_memory_usage --route_chan_width 100 --max_router_iterations 100 --router_lookahead map --flat_routing true
+script_params_common=-track_memory_usage --route_chan_width 100 --max_router_iterations 100 --router_lookahead map --flat_routing on
 script_params_list_add =
 script_params_list_add = --router_algorithm parallel --num_workers 4