diff --git a/src/adsb/process_icao_chunk.py b/src/adsb/process_icao_chunk.py
index d2eed6a..f208a85 100644
--- a/src/adsb/process_icao_chunk.py
+++ b/src/adsb/process_icao_chunk.py
@@ -1,18 +1,12 @@
 """
-Processes a chunk of ICAOs from pre-extracted trace files.
+Processes a chunk of ICAOs from pre-extracted trace files for a single day.
 This is the map phase of the map-reduce pipeline.
 
-Supports both single-day (daily) and multi-day (historical) modes.
-
 Expects extract_dir to already exist with trace files.
 Reads ICAO manifest to determine which ICAOs to process based on chunk-id.
 
 Usage:
-    # Daily mode (single day)
-    python -m src.adsb.process_icao_chunk --chunk-id 0 --total-chunks 4
-    
-    # Historical mode (date range)
-    python -m src.adsb.process_icao_chunk --chunk-id 0 --total-chunks 4 --start-date 2024-01-01 --end-date 2024-01-07
+    python -m src.adsb.process_icao_chunk --chunk-id 0 --total-chunks 4 --date 2026-01-01
 """
 import gc
 import os
@@ -248,69 +242,11 @@ def process_single_day(
     return process_chunk(chunk_id, total_chunks, trace_map, icaos, date_str)
 
 
-def process_date_range(
-    chunk_id: int,
-    total_chunks: int,
-    start_date: datetime,
-    end_date: datetime,
-) -> str | None:
-    """Process a date range for this chunk.
-    
-    Combines trace files from all days in the range.
-    
-    Args:
-        chunk_id: This chunk's ID (0-indexed)
-        total_chunks: Total number of chunks
-        start_date: Start date (inclusive)
-        end_date: End date (inclusive)
-    """
-    start_str = start_date.strftime("%Y-%m-%d")
-    end_str = end_date.strftime("%Y-%m-%d")
-    manifest_id = f"{start_str}_{end_str}"
-    
-    print(f"Processing date range: {start_str} to {end_str}")
-    
-    # Build combined trace map from all days - keep ALL trace files (one ICAO may have multiple days)
-    combined_trace_map: dict[str, list[str]] = {}
-    current = start_date
-    
-    # Both start and end are inclusive
-    while current <= end_date:
-        version_date = f"v{current.strftime('%Y.%m.%d')}"
-        extract_dir = os.path.join(OUTPUT_DIR, f"{version_date}-planes-readsb-prod-0.tar_0")
-        
-        if os.path.isdir(extract_dir):
-            trace_map = build_trace_file_map(extract_dir)
-            # Collect ALL trace files for each ICAO across all days
-            for icao, trace_file in trace_map.items():
-                if icao not in combined_trace_map:
-                    combined_trace_map[icao] = []
-                combined_trace_map[icao].append(trace_file)
-            print(f"  {current.strftime('%Y-%m-%d')}: {len(trace_map)} trace files")
-        else:
-            print(f"  {current.strftime('%Y-%m-%d')}: no extract directory")
-        
-        current += timedelta(days=1)
-    
-    if not combined_trace_map:
-        print("No trace files found in date range")
-        return None
-    
-    print(f"Combined trace map: {len(combined_trace_map)} ICAOs with {sum(len(files) for files in combined_trace_map.values())} total trace files")
-    
-    icaos = read_manifest(manifest_id)
-    print(f"Total ICAOs in manifest: {len(icaos)}")
-    
-    return process_chunk(chunk_id, total_chunks, combined_trace_map, icaos, manifest_id)
-
-
 def main():
-    parser = argparse.ArgumentParser(description="Process a chunk of ICAOs")
+    parser = argparse.ArgumentParser(description="Process a chunk of ICAOs for a single day")
     parser.add_argument("--chunk-id", type=int, required=True, help="Chunk ID (0-indexed)")
     parser.add_argument("--total-chunks", type=int, required=True, help="Total number of chunks")
     parser.add_argument("--date", type=str, help="Single date in YYYY-MM-DD format (default: yesterday)")
-    parser.add_argument("--start-date", type=str, help="Start date for range (YYYY-MM-DD)")
-    parser.add_argument("--end-date", type=str, help="End date for range (YYYY-MM-DD)")
     args = parser.parse_args()
     
     print(f"Processing chunk {args.chunk_id}/{args.total_chunks}")
@@ -326,19 +262,13 @@ def main():
     else:
         print(f"  Directory does not exist!")
     
-    # Determine mode: single day or date range
-    if args.start_date and args.end_date:
-        # Historical mode
-        start_date = datetime.strptime(args.start_date, "%Y-%m-%d")
-        end_date = datetime.strptime(args.end_date, "%Y-%m-%d")
-        output_path = process_date_range(args.chunk_id, args.total_chunks, start_date, end_date)
+    # Process single day
+    if args.date:
+        target_day = datetime.strptime(args.date, "%Y-%m-%d")
     else:
-        # Daily mode
-        if args.date:
-            target_day = datetime.strptime(args.date, "%Y-%m-%d")
-        else:
-            target_day = get_target_day()
-        output_path = process_single_day(args.chunk_id, args.total_chunks, target_day)
+        target_day = get_target_day()
+    
+    output_path = process_single_day(args.chunk_id, args.total_chunks, target_day)
     
     if output_path:
         print(f"Output: {output_path}")
@@ -347,4 +277,4 @@ def main():
 
 
 if __name__ == "__main__":
-    main()
+    main() 
\ No newline at end of file